[ES|QL] Fixes Incomplete string escaping or encoding error (#193384)

## Summary

Closes elastic/kibana-team#1087

I think that this change will close the second problem. Not 100% sure
but this is how I interpret it

(cherry picked from commit 88163b0)

packages/kbn-esql-utils/src/utils/append_to_query.ts

@@ -36,7 +36,7 @@ export function appendWhereClauseToESQLQuery(
     default:
       operator = '==';
   }
-  let filterValue = typeof value === 'string' ? `"${value.replace(/"/g, '\\"')}"` : value;
+  let filterValue = typeof value === 'string' ? `"${value.replace(/\"/g, '\\"')}"` : value;
   // Adding the backticks here are they are needed for special char fields
   let fieldName = `\`${field}\``;