workload/scheamchanger: fix unknown schema retry detection

Fixes: #89146

Previously, when we added logic to retry unknown schema errors,
the regex used was unfortunately out of sync with the actual
error generated. This patch fixes the regex to have the correct
string, since those errors were not properly retried.

Release note: None

pkg/workload/schemachange/error_screening.go

@@ -1122,7 +1122,9 @@ SELECT count(*) FROM %s
 }
 
 var (
-	regexpUnknownSchemaErr = regexp.MustCompile(`unknown schema \[\d+\]`)
+	// regexpUnknownSchemaErr matches unknown schema errors with
+	// a descriptor ID, which will have the form: unknown schema "[123]"
+	regexpUnknownSchemaErr = regexp.MustCompile(`unknown schema "\[\d+]"`)
 )
 
 // checkAndAdjustForUnknownSchemaErrors in certain contexts we will attempt to
@@ -1135,7 +1137,7 @@ func (og *operationGenerator) checkAndAdjustForUnknownSchemaErrors(err error) er
 		if regexpUnknownSchemaErr.MatchString(pgErr.Message) {
 			og.opGenLog.WriteString(fmt.Sprintf("Rolling back due to unknown schema error %v",
 				err))
-			// Force a rollback and log inside the oepration generator.
+			// Force a rollback and log inside the operation generator.
 			return errors.Mark(err, errRunInTxnRbkSentinel)
 		}
 	}