Postgres: Switch the datasource plugin from lib/pq to pgx (#103961)

* Create libpqToPGX feature toggle

* Refactor PostgreSQL datasource to support PGX with feature toggle

- Updated `ProvideService` to accept feature toggles for enabling PGX.
- Modified integration tests to use the new PGX connection method.
- Introduced new functions for handling PGX connections and queries.
- Enhanced TLS configuration handling for PostgreSQL connections.
- Updated existing tests to ensure compatibility with PGX and new connection methods.

* Update PostgreSQL datasource to enhance connection pooling and error handling

- Increased `MaxOpenConns` to 10 in integration tests for improved connection management.
- Refactored connection handling in `newPostgresPGX` to return a connection pool instead of a single connection.
- Updated health check error handling to utilize context and feature toggles for better error reporting.
- Adjusted `DisposePGX` method to close the connection pool properly.
- Enhanced query execution to acquire connections from the pool, ensuring efficient resource usage.

* Cleanup

* Revert postgres_test unnecessary changes

* Rename feature toggle from `libpqToPGX` to `postgresDSUsePGX`

* Add null check to dispose method

* Fix lint issues

* Refactor connection string generation

* Address comment in health check file

* Rename p to pool

* Refactor executeQueryPGX and split into multiple functions

* Fix lint issues

* The returning error message from PGX is enough no need to separate the error code.

* Move TLS handling to newPostgresPGX function

* Disable ssl for integration tests

* Use MaxIdleConns option

* Remove old feature toggle

* Rename`generateConnectionConfigPGX` to `generateConnectionStringPGX`

* Add back part of the error messages

* Don't show max idle connections option when PGX enabled

* Address comments from Sriram

* Add back Sriram's changes

* PostgreSQL: Rework tls manager to use temporary files instead (#105330)

* Rework tls manager to use temporary files instead

* Lint and test fixes

* Update pkg/tsdb/grafana-postgresql-datasource/postgres.go

Co-authored-by: Ivana Huckova <30407135+ivanahuckova@users.noreply.github.com>

* Update betterer

---------

Co-authored-by: Ivana Huckova <30407135+ivanahuckova@users.noreply.github.com>

---------

Co-authored-by: Ivana Huckova <30407135+ivanahuckova@users.noreply.github.com>

pkg/tsdb/grafana-postgresql-datasource/postgres_snapshot_test.go

@@ -149,10 +149,11 @@ func TestIntegrationPostgresSnapshots(t *testing.T) {
 			}
 
 			jsonData := sqleng.JsonData{
-				MaxOpenConns:        0,
+				MaxOpenConns:        10,
 				MaxIdleConns:        2,
 				ConnMaxLifetime:     14400,
 				Timescaledb:         false,
+				Mode:                "disable",
 				ConfigurationMethod: "file-path",
 			}
 
@@ -165,13 +166,12 @@ func TestIntegrationPostgresSnapshots(t *testing.T) {
 
 			cnnstr := getCnnStr()
 
-			db, handler, err := newPostgres(context.Background(), "error", 10000, dsInfo, cnnstr, logger, backend.DataSourceInstanceSettings{})
+			p, handler, err := newPostgresPGX(context.Background(), "error", 10000, dsInfo, cnnstr, logger, backend.DataSourceInstanceSettings{})
 
 			t.Cleanup((func() {
-				_, err := db.Exec("DROP TABLE tbl")
-				require.NoError(t, err)
-				err = db.Close()
+				_, err := p.Exec(context.Background(), "DROP TABLE tbl")
 				require.NoError(t, err)
+				p.Close()
 			}))
 
 			require.NoError(t, err)
@@ -181,12 +181,12 @@ func TestIntegrationPostgresSnapshots(t *testing.T) {
 
 			rawSQL, sql := readSqlFile(sqlFilePath)
 
-			_, err = db.Exec(sql)
+			_, err = p.Exec(context.Background(), sql)
 			require.NoError(t, err)
 
 			query := makeQuery(rawSQL, test.format)
 
-			result, err := handler.QueryData(context.Background(), &query)
+			result, err := handler.QueryDataPGX(context.Background(), &query)
 			require.Len(t, result.Responses, 1)
 			response, found := result.Responses["A"]
 			require.True(t, found)