refactor(database): exchange connection pool (#8325)

# Which Problems Are Solved

The connection pool of go uses a high amount of database connections.

# How the Problems Are Solved

The standard lib connection pool was replaced by `pgxpool.Pool`

# Additional Changes

The `db.BeginTx`-spans are removed because they cause to much noise in
the traces.

# Additional Context

- part of https://github.com/zitadel/zitadel/issues/7639

internal/query/current_state.go

@@ -90,9 +90,7 @@ func (q *Queries) latestState(ctx context.Context, projections ...table) (state
 }
 
 func (q *Queries) ClearCurrentSequence(ctx context.Context, projectionName string) (err error) {
-	ctx, spanBeginTx := tracing.NewNamedSpan(ctx, "db.BeginTx")
 	tx, err := q.client.BeginTx(ctx, nil)
-	spanBeginTx.EndWithError(err)
 	if err != nil {
 		return zerrors.ThrowInternal(err, "QUERY-9iOpr", "Errors.RemoveFailed")
 	}
@@ -205,7 +203,7 @@ func reset(ctx context.Context, tx *sql.Tx, tables []string, projectionName stri
 	if err != nil {
 		return zerrors.ThrowInternal(err, "QUERY-Ff3tw", "Errors.RemoveFailed")
 	}
-	_, err = tx.Exec(update, args...)
+	_, err = tx.ExecContext(ctx, update, args...)
 	if err != nil {
 		return zerrors.ThrowInternal(err, "QUERY-NFiws", "Errors.RemoveFailed")
 	}