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/locker_test.go

@@ -1,63 +0,0 @@
-package postgres
-
-import (
-	"sync"
-	"testing"
-	"time"
-
-	"github.com/stretchr/testify/require"
-)
-
-func TestIntegrationLocker(t *testing.T) {
-	if testing.Short() {
-		t.Skip("Tests with Sleep")
-	}
-	const notUpdated = "not_updated"
-	const atThread1 = "at_thread_1"
-	const atThread2 = "at_thread_2"
-	t.Run("Should lock for same keys", func(t *testing.T) {
-		updated := notUpdated
-		locker := newLocker()
-		locker.Lock(1)
-		var wg sync.WaitGroup
-		wg.Add(1)
-		defer func() {
-			locker.Unlock(1)
-			wg.Wait()
-		}()
-
-		go func() {
-			locker.RLock(1)
-			defer func() {
-				locker.RUnlock(1)
-				wg.Done()
-			}()
-			require.Equal(t, atThread1, updated, "Value should be updated in different thread")
-			updated = atThread2
-		}()
-		time.Sleep(time.Millisecond * 10)
-		require.Equal(t, notUpdated, updated, "Value should not be updated in different thread")
-		updated = atThread1
-	})
-
-	t.Run("Should not lock for different keys", func(t *testing.T) {
-		updated := notUpdated
-		locker := newLocker()
-		locker.Lock(1)
-		defer locker.Unlock(1)
-		var wg sync.WaitGroup
-		wg.Add(1)
-		go func() {
-			locker.RLock(2)
-			defer func() {
-				locker.RUnlock(2)
-				wg.Done()
-			}()
-			require.Equal(t, notUpdated, updated, "Value should not be updated in different thread")
-			updated = atThread2
-		}()
-		wg.Wait()
-		require.Equal(t, atThread2, updated, "Value should be updated in different thread")
-		updated = atThread1
-	})
-}