database/sql: fix TestTxStmtDeadlock test

Drop error check because errors can be
not only ErrTxDone for tx stmt executions,
and the purpose of the test is just reproducing
deadlock.

Fixes #42259

Change-Id: I9e7105ada1403ec7064dcc1c3385b36893a1c195
Reviewed-on: https://go-review.googlesource.com/c/go/+/266097
Reviewed-by: Daniel Theophanes <kardianos@gmail.com>
Trust: Emmanuel Odeke <emmanuel@orijtech.com>
Run-TryBot: Emmanuel Odeke <emmanuel@orijtech.com>
TryBot-Result: Go Bot <gobot@golang.org>

src/database/sql/sql_test.go

@@ -2828,12 +2828,10 @@ func TestTxStmtDeadlock(t *testing.T) {
 	}
 	// Run number of stmt queries to reproduce deadlock from context cancel
 	for i := 0; i < 1e3; i++ {
+		// Encounter any close related errors (e.g. ErrTxDone, stmt is closed)
+		// is expected due to context cancel.
 		_, err = stmt.Query(1)
 		if err != nil {
-			// Encounter ErrTxDone here is expected due to context cancel
-			if err != ErrTxDone {
-				t.Fatalf("unexpected error while executing stmt, err: %v", err)
-			}
 			break
 		}
 	}