[8.x] Document the reason for skipped APM tests (#201214) (#201238)

# Backport

This will backport the following commits from `main` to `8.x`:
- [Document the reason for skipped APM tests
(#201214)](#201214)

<!--- Backport version: 9.4.3 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

<!--BACKPORT [{"author":{"name":"Milosz
Marcinkowski","email":"[email protected]"},"sourceCommit":{"committedDate":"2024-11-21T16:37:05Z","message":"Document
the reason for skipped APM tests (#201214)\n\nCloses #199843\r\n\r\n###
Summary\r\n\r\nThis PR documents the reason for skipped Indices
diagnostics API tests\r\nto avoid confusion in the future. APM
diagnostics is an experimental\r\ninternal tool. Indices diagnostics
determine whether ingest pipelines\r\nwere installed correctly by
verifying the presence of the\r\n`observer.version` field in grok
processor, this approach isn't reliable\r\nanymore. We should consider
implementing improvement or sunsetting the\r\nfeature if there is no
maintainer.","sha":"fb35ae45df41b324a53669a735779b15d30f332f","branchLabelMapping":{"^v9.0.0$":"main","^v8.18.0$":"8.x","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["release_note:skip","v9.0.0","backport:prev-minor"],"title":"Document
the reason for skipped APM
tests","number":201214,"url":"https://github.com/elastic/kibana/pull/201214","mergeCommit":{"message":"Document
the reason for skipped APM tests (#201214)\n\nCloses #199843\r\n\r\n###
Summary\r\n\r\nThis PR documents the reason for skipped Indices
diagnostics API tests\r\nto avoid confusion in the future. APM
diagnostics is an experimental\r\ninternal tool. Indices diagnostics
determine whether ingest pipelines\r\nwere installed correctly by
verifying the presence of the\r\n`observer.version` field in grok
processor, this approach isn't reliable\r\nanymore. We should consider
implementing improvement or sunsetting the\r\nfeature if there is no
maintainer.","sha":"fb35ae45df41b324a53669a735779b15d30f332f"}},"sourceBranch":"main","suggestedTargetBranches":[],"targetPullRequestStates":[{"branch":"main","label":"v9.0.0","branchLabelMappingKey":"^v9.0.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/201214","number":201214,"mergeCommit":{"message":"Document
the reason for skipped APM tests (#201214)\n\nCloses #199843\r\n\r\n###
Summary\r\n\r\nThis PR documents the reason for skipped Indices
diagnostics API tests\r\nto avoid confusion in the future. APM
diagnostics is an experimental\r\ninternal tool. Indices diagnostics
determine whether ingest pipelines\r\nwere installed correctly by
verifying the presence of the\r\n`observer.version` field in grok
processor, this approach isn't reliable\r\nanymore. We should consider
implementing improvement or sunsetting the\r\nfeature if there is no
maintainer.","sha":"fb35ae45df41b324a53669a735779b15d30f332f"}}]}]
BACKPORT-->

Co-authored-by: Milosz Marcinkowski <[email protected]>

x-pack/test/api_integration/deployment_agnostic/apis/observability/apm/diagnostics/indices.spec.ts

@@ -21,9 +21,10 @@ export default function ApiTest({ getService }: DeploymentAgnosticFtrProviderCon
 
   let apmSynthtraceEsClient: ApmSynthtraceEsClient;
 
-  describe('Diagnostics: Indices', () => {
-    describe.skip('When there is no data', () => {
-      it('returns empty response`', async () => {
+  // Failing tests were skipped because the current solution for verifying ingest pipelines needs improvement
+  describe.skip('Diagnostics: Indices', () => {
+    describe('When there is no data', () => {
+      it('returns empty response', async () => {
         const { status, body } = await apmApiClient.adminUser({
           endpoint: 'GET /internal/apm/diagnostics',
         });
@@ -34,7 +35,7 @@ export default function ApiTest({ getService }: DeploymentAgnosticFtrProviderCon
       });
     });
 
-    describe.skip('When data is ingested', () => {
+    describe('When data is ingested', () => {
       before(async () => {
         const instance = apm
           .service({ name: 'synth-go', environment: 'production', agentName: 'go' })
@@ -68,7 +69,7 @@ export default function ApiTest({ getService }: DeploymentAgnosticFtrProviderCon
       });
     });
 
-    describe.skip('When data is ingested without the necessary index templates', () => {
+    describe('When data is ingested without the necessary index templates', () => {
       before(async () => {
         await es.indices.deleteDataStream({ name: 'traces-apm-*' });
         await es.indices.deleteIndexTemplate({ name: ['traces-apm'] });
@@ -114,7 +115,7 @@ export default function ApiTest({ getService }: DeploymentAgnosticFtrProviderCon
       });
     });
 
-    describe.skip('ingest pipelines', () => {
+    describe('ingest pipelines', () => {
       before(async () => {
         const instance = apm
           .service({ name: 'synth-go', environment: 'production', agentName: 'go' })
@@ -138,7 +139,7 @@ export default function ApiTest({ getService }: DeploymentAgnosticFtrProviderCon
         await apmSynthtraceEsClient.clean();
       });
 
-      describe.skip('an ingest pipeline is removed', () => {
+      describe('an ingest pipeline is removed', () => {
         before(async () => {
           const datastreamToUpdate = await es.indices.getDataStream({
             name: 'metrics-apm.internal-default',
@@ -168,7 +169,7 @@ export default function ApiTest({ getService }: DeploymentAgnosticFtrProviderCon
         });
       });
 
-      describe.skip('an ingest pipeline is changed', () => {
+      describe('an ingest pipeline is changed', () => {
         before(async () => {
           const datastreamToUpdate = await es.indices.getDataStream({
             name: 'metrics-apm.internal-default',