[Synthetics] Fix location remove via public API !! (#199170)

## Summary

Fixes #199108

Fix location remove via public API !!

### Testing

Create a Monitor that is configured in two locations:
```
POST kbn:/api/synthetics/monitors
{
  "type": "http",
  "name": "healthcheck",
  "url": "https://www.elastic.co",
  "locations": ["united_kingdom", "germany"]
}
```
Extract from the response the config_id
Update the monitor to remove one location
```
PUT kbn:/api/synthetics/monitors/<config-id>
{
  "type": "http",
  "name": "healthcheck",
  "url": "https://www.elastic.co",
  "locations": ["united_kingdom"]
}
```

This should remove Germany location from monitor !!

(cherry picked from commit 4a34105)

x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/utils.test.ts

@@ -33,6 +33,11 @@ describe('parseMonitorLocations', () => {
     id: 'local',
     isServiceManaged: true,
   };
+  const localLoc2 = {
+    label: 'Local 2',
+    id: 'local2',
+    isServiceManaged: true,
+  };
 
   it('should return expected', function () {
     const result = parseMonitorLocations({
@@ -81,6 +86,20 @@ describe('parseMonitorLocations', () => {
     });
   });
 
+  it('should handle editing location', function () {
+    const result = parseMonitorLocations(
+      {
+        locations: ['local'],
+      } as any,
+      [localLoc, localLoc2]
+    );
+
+    expect(result).toEqual({
+      locations: ['local'],
+      privateLocations: [],
+    });
+  });
+
   it('should add private locations to existing', function () {
     const result = parseMonitorLocations(
       {
@@ -91,7 +110,7 @@ describe('parseMonitorLocations', () => {
 
     expect(result).toEqual({
       locations: ['local'],
-      privateLocations: ['test-private-location-2', 'test-private-location'],
+      privateLocations: ['test-private-location-2'],
     });
   });
 
@@ -185,4 +204,19 @@ describe('parseMonitorLocations', () => {
       privateLocations: [],
     });
   });
+
+  it('should handle private location objects', function () {
+    const result = parseMonitorLocations(
+      {
+        locations: [pvtLoc1],
+      } as any,
+      [localLoc, pvtLoc1],
+      true
+    );
+
+    expect(result).toEqual({
+      locations: [],
+      privateLocations: ['test-private-location'],
+    });
+  });
 });

x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/utils.ts

@@ -25,7 +25,7 @@ export const getPrivateLocationsForMonitor = async (
 export const parseMonitorLocations = (
   monitorPayload: CreateMonitorPayLoad,
   prevLocations?: MonitorFields['locations'],
-  internal: boolean = false
+  internal = false
 ) => {
   const { locations, private_locations: privateLocations } = monitorPayload;
 
@@ -42,41 +42,33 @@ export const parseMonitorLocations = (
     pvtLocs = prevLocations.filter((loc) => !loc.isServiceManaged).map((loc) => loc.id);
   } else {
     if (prevLocations && !internal) {
+      const prevPublicLocs = prevLocations
+        .filter((loc) => loc.isServiceManaged)
+        .map((loc) => loc.id);
+      const prevPrivateLocs = prevLocations
+        .filter((loc) => !loc.isServiceManaged)
+        .map((loc) => loc.id);
+
       if (!locations && !privateLocations) {
-        locs = prevLocations.filter((loc) => loc.isServiceManaged).map((loc) => loc.id);
-        pvtLocs = prevLocations.filter((loc) => !loc.isServiceManaged).map((loc) => loc.id);
+        locs = prevPublicLocs;
+        pvtLocs = prevPrivateLocs;
       } else {
         if (!privateLocations) {
-          pvtLocs = [
-            ...(pvtLocs ?? []),
-            ...prevLocations.filter((loc) => !loc.isServiceManaged).map((loc) => loc.id),
-          ];
+          pvtLocs = [...(pvtLocs ?? []), ...prevPrivateLocs];
           if (locations?.length === 0) {
             locs = [];
-          } else {
-            locs = [
-              ...(locs ?? []),
-              ...prevLocations.filter((loc) => loc.isServiceManaged).map((loc) => loc.id),
-            ];
           }
         }
         if (!locations) {
-          locs = [
-            ...(locs ?? []),
-            ...prevLocations.filter((loc) => loc.isServiceManaged).map((loc) => loc.id),
-          ];
+          locs = [...(locs ?? []), ...prevPublicLocs];
           if (privateLocations?.length === 0) {
             pvtLocs = [];
-          } else {
-            pvtLocs = [
-              ...(pvtLocs ?? []),
-              ...prevLocations.filter((loc) => !loc.isServiceManaged).map((loc) => loc.id),
-            ];
           }
         }
       }
     }
   }
+
   return {
     locations: Array.from(new Set(locs)),
     privateLocations: Array.from(new Set(pvtLocs)),

x-pack/test/api_integration/apis/synthetics/edit_monitor_public_api.ts

@@ -270,14 +270,15 @@ export default function ({ getService }: FtrProviderContext) {
           ...updates,
           revision: 4,
           url: 'https://www.google.com',
-          locations: [localLoc, pvtLoc],
+          locations: [pvtLoc],
         })
       );
     });
 
     it('can remove private location from existing monitor', async () => {
-      const monitor = {
-        private_locations: [],
+      let monitor: any = {
+        locations: [localLoc.id],
+        private_locations: [pvtLoc.id],
       };
 
       const { body: result } = await editMonitorAPI(monitorId, monitor);
@@ -288,6 +289,22 @@ export default function ({ getService }: FtrProviderContext) {
           ...updates,
           revision: 5,
           url: 'https://www.google.com',
+          locations: [localLoc, pvtLoc],
+        })
+      );
+
+      monitor = {
+        private_locations: [],
+      };
+
+      const { body: result1 } = await editMonitorAPI(monitorId, monitor);
+
+      expect(result1).eql(
+        omitMonitorKeys({
+          ...defaultFields,
+          ...updates,
+          revision: 6,
+          url: 'https://www.google.com',
           locations: [localLoc],
         })
       );