Revert "Postgres: Switch the datasource plugin from lib/pq to pgx" (#83760)

Revert "Postgres: Switch the datasource plugin from lib/pq to pgx (#81353)"

This reverts commit 8c18d06386c87f2786119ea9a6334e35e4181cbe.

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

@@ -3,17 +3,33 @@ package postgres
 import (
 	"context"
 	"net"
+	"time"
 
+	"github.com/lib/pq"
 	"golang.org/x/net/proxy"
 )
 
-type PgxDialFunc = func(ctx context.Context, network string, address string) (net.Conn, error)
-
-func newPgxDialFunc(dialer proxy.Dialer) PgxDialFunc {
-	dialFunc :=
-		func(ctx context.Context, network string, addr string) (net.Conn, error) {
-			return dialer.Dial(network, addr)
-		}
-
-	return dialFunc
+// we wrap the proxy.Dialer to become dialer that the postgres module accepts
+func newPostgresProxyDialer(dialer proxy.Dialer) pq.Dialer {
+	return &postgresProxyDialer{d: dialer}
+}
+
+var _ pq.Dialer = (&postgresProxyDialer{})
+
+// postgresProxyDialer implements the postgres dialer using a proxy dialer, as their functions differ slightly
+type postgresProxyDialer struct {
+	d proxy.Dialer
+}
+
+// Dial uses the normal proxy dial function with the updated dialer
+func (p *postgresProxyDialer) Dial(network, addr string) (c net.Conn, err error) {
+	return p.d.Dial(network, addr)
+}
+
+// DialTimeout uses the normal postgres dial timeout function with the updated dialer
+func (p *postgresProxyDialer) DialTimeout(network, address string, timeout time.Duration) (net.Conn, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+
+	return p.d.(proxy.ContextDialer).DialContext(ctx, network, address)
 }