kvfollowerreadsccl: fix tests when run as secondary tenants

We probabilistically run SQL using secondary tenant connections
in tests. This breaks TestBoundedStalenessDataDriven and
TestFollowerReadsWithStaleDescriptor.

TestBoundedStalenessDataDriven can't make assertions on log lines
originating from kv server as these are redacted before they're sent
to secondary tenants. This patch fixes this by flipping a cluster
setting to disable such redaction.

TestFollowerReadsWithStaleDescriptor is not as clear cut, so for now
we simply eschew running it with a secondary tenant.

Release note: None

pkg/ccl/kvccl/kvfollowerreadsccl/boundedstaleness_test.go

@@ -299,6 +299,13 @@ func TestBoundedStalenessDataDriven(t *testing.T) {
 		tc := testcluster.StartTestCluster(t, 3, clusterArgs)
 		defer tc.Stopper().Stop(ctx)
 
+		// This test may probabilistically execute its SQL as a secondary tenant. It
+		// also traces queries and makes assertions on whether log lines indicate
+		// requests were served via follower reads. As these log lines originate
+		// down in kvserver we disable their redaction.
+		systemTenantSQL := sqlutils.MakeSQLRunner(tc.StorageClusterConn())
+		systemTenantSQL.Exec(t, `SET CLUSTER SETTING server.secondary_tenants.redact_trace.enabled = 'false'`)
+
 		savedTraceStmt := ""
 		datadriven.RunTest(t, path, func(t *testing.T, d *datadriven.TestData) string {
 			// Early exit non-query execution related commands.

pkg/ccl/kvccl/kvfollowerreadsccl/followerreads_test.go

@@ -568,13 +568,17 @@ func TestFollowerReadsWithStaleDescriptor(t *testing.T) {
 	tc := testcluster.StartTestCluster(t, 4,
 		base.TestClusterArgs{
 			ReplicationMode: base.ReplicationManual,
-			ServerArgs:      base.TestServerArgs{UseDatabase: "t"},
+			ServerArgs: base.TestServerArgs{
+				DisableDefaultTestTenant: true,
+				UseDatabase:              "t",
+			},
 			// n4 pretends to have low latency to n2 and n3, so that it tries to use
 			// them for follower reads.
 			// Also, we're going to collect a trace of the test's final query.
 			ServerArgsPerNode: map[int]base.TestServerArgs{
 				3: {
-					UseDatabase: "t",
+					DisableDefaultTestTenant: true,
+					UseDatabase:              "t",
 					Knobs: base.TestingKnobs{
 						KVClient: &kvcoord.ClientTestingKnobs{
 							// Inhibit the checking of connection health done by the