testccl/sqlccl: unskip TestExplainRedactDDL

`TestExplainRedactDDL` is a randomized SQL test which runs variants of
`EXPLAIN (REDACT)` on random SQL statements and checks that an injected
poison string is always redacted in the output. It is very similar to
another randomized test, `TestExplainRedact`, but also includes DDL in
the random statements.

During development of v23.1 this test was skipped because the random DDL
statements were running into other bugs unrelated to redaction. Now that
things are more stable, let's unskip this test.

Fixes: #99005

Epic: None

Release note: None

pkg/ccl/testccl/sqlccl/explain_test.go

@@ -18,7 +18,6 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/lexbase"
 	"github.com/cockroachdb/cockroach/pkg/sql/tests"
 	"github.com/cockroachdb/cockroach/pkg/testutils/serverutils"
-	"github.com/cockroachdb/cockroach/pkg/testutils/skip"
 	"github.com/cockroachdb/cockroach/pkg/util/leaktest"
 	"github.com/cockroachdb/cockroach/pkg/util/log"
 	"github.com/cockroachdb/cockroach/pkg/util/randutil"
@@ -33,9 +32,6 @@ func TestExplainRedactDDL(t *testing.T) {
 	defer leaktest.AfterTest(t)()
 	defer log.Scope(t).Close(t)
 
-	skip.WithIssue(t, 99005)
-	skip.UnderStressWithIssue(t, 99005)
-
 	const numStatements = 10
 
 	ctx := context.Background()