sql: fix "no user specified" errors in statement bundles

A regression was introduced in cockroachdb#71246 that caused errors when running
internal queries to populate files in statement bundles. As a result,
critical information was missing from the `env.sql`, `schema.sql`, and
`stats*.sql` files. This commit fixes the issue by using an
`InternalExecutorOverride` with a root user override. A root user is
required because a node user is insufficient - it does not have
privileges on user-defined relations which is needed for the
`SHOW CREATE` queries that populate `schema.sql`.

Fixes cockroachdb#80396

Release note: None

pkg/sql/explain_bundle.go

@@ -19,6 +19,7 @@ import (
 	"strings"
 
 	"github.com/cockroachdb/cockroach/pkg/kv"
+	"github.com/cockroachdb/cockroach/pkg/security"
 	"github.com/cockroachdb/cockroach/pkg/settings"
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/colinfo"
 	"github.com/cockroachdb/cockroach/pkg/sql/opt/cat"
@@ -431,14 +432,19 @@ func makeStmtEnvCollector(ctx context.Context, ie *InternalExecutor) stmtEnvColl
 	return stmtEnvCollector{ctx: ctx, ie: ie}
 }
 
+// explainBundleUserSessionsDataOverride is an InternalExecutorOverride which
+// overrides the users to the RootUser.
+var explainBundleUserSessionDataOverride = sessiondata.InternalExecutorOverride{
+	User: security.MakeSQLUsernameFromPreNormalizedString(security.RootUser)}
+
 // environmentQuery is a helper to run a query that returns a single string
 // value.
 func (c *stmtEnvCollector) query(query string) (string, error) {
 	row, err := c.ie.QueryRowEx(
 		c.ctx,
 		"stmtEnvCollector",
 		nil, /* txn */
-		sessiondata.NoSessionDataOverride,
+		explainBundleUserSessionDataOverride,
 		query,
 	)
 	if err != nil {
@@ -574,7 +580,7 @@ func (c *stmtEnvCollector) PrintClusterSettings(w io.Writer) error {
 		c.ctx,
 		"stmtEnvCollector",
 		nil, /* txn */
-		sessiondata.NoSessionDataOverride,
+		explainBundleUserSessionDataOverride,
 		"SELECT variable, value, description FROM [ SHOW ALL CLUSTER SETTINGS ]",
 	)
 	if err != nil {

pkg/sql/explain_bundle_test.go

@@ -189,16 +189,25 @@ func checkBundle(t *testing.T, text, tableName string, expectedFiles ...string)
 		}
 		files = append(files, f.Name)
 
+		r, err := f.Open()
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer r.Close()
+		contents, err := ioutil.ReadAll(r)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if strings.Contains(string(contents), "-- error") {
+			t.Errorf(
+				"expected no errors in %s, file contents:\n%s",
+				f.Name,
+				string(contents),
+			)
+		}
+
 		if f.Name == "schema.sql" {
-			r, err := f.Open()
-			if err != nil {
-				t.Fatal(err)
-			}
-			defer r.Close()
-			contents, err := ioutil.ReadAll(r)
-			if err != nil {
-				t.Fatal(err)
-			}
 			if !strings.Contains(string(contents), tableName) {
 				t.Errorf(
 					"expected table name to appear in schema.sql. tableName: %s\nfile contents:\n%s",