test(source/postgres): fix list_database_stats integration test (#2235)

## Description
The list_database_stats test fails intermittently when run in parallel
on shared instances. Specifically, the "filter by tablespace" and "sort
by size" test cases fail because they encounter unexpected databases in
the pg_default tablespace created by concurrent test runs.
This PR narrows the scope of these test cases by filtering for specific
database names. This ensures assertions remain isolated to the current
test run regardless of other databases present in the shared
environment.

```
 go test -tags=integration tests/postgres/postgres_integration_test.go
ok      command-line-arguments  14.455s
```

> Should include a concise description of the changes (bug or feature),
it's
> impact, along with a summary of the solution

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🛠️ Fixes #<1738>

tests/tool.go

@@ -2452,15 +2452,15 @@ func RunPostgresListDatabaseStatsTest(t *testing.T, ctx context.Context, pool *p
 		},
 		{
 			name:           "filter by tablespace",
-			requestBody:    bytes.NewBuffer([]byte(`{"default_tablespace": "pg_default"}`)),
+			requestBody:    bytes.NewBuffer([]byte(fmt.Sprintf(`{"default_tablespace": "pg_default", "database_name": "%s"}`, dbName1))),
 			wantStatusCode: http.StatusOK,
-			want:           []map[string]interface{}{db1Want, db2Want},
+			want:           []map[string]interface{}{db1Want},
 		},
 		{
-			name:           "sort by size (desc)",
-			requestBody:    bytes.NewBuffer([]byte(`{"sort_by": "size"}`)),
+			name:           "sort by size",
+			requestBody:    bytes.NewBuffer([]byte(fmt.Sprintf(`{"sort_by": "size", "database_name": "%s"}`, dbName2))),
 			wantStatusCode: http.StatusOK,
-			want:           []map[string]interface{}{db1Want, db2Want},
+			want:           []map[string]interface{}{db2Want},
 		},
 	}
 
@@ -2472,7 +2472,6 @@ func RunPostgresListDatabaseStatsTest(t *testing.T, ctx context.Context, pool *p
 			if resp.StatusCode != tc.wantStatusCode {
 				t.Fatalf("wrong status code: got %d, want %d, body: %s", resp.StatusCode, tc.wantStatusCode, string(body))
 			}
-
 			var bodyWrapper struct {
 				Result json.RawMessage `json:"result"`
 			}