kvserver: setup ranges in large unsplittable replicate test

`TestLargeUnsplittableRangeReplicate` would fail when the SQL query to
show the table's replicas returned no results for the unsplittable range
being tested. No results would be returned when the table split was
delayed.

Update the test to insert a split at the first row, as well as the
existing split at the second row. This avoids the first range starting
with 5 replicas and the test's reliance on timely span config splits.

Resolves: #112774
Release note: None

pkg/kv/kvserver/replicate_queue_test.go

@@ -1774,8 +1774,6 @@ func TestLargeUnsplittableRangeReplicate(t *testing.T) {
 		base.TestClusterArgs{
 			ReplicationMode: base.ReplicationAuto,
 			ServerArgs: base.TestServerArgs{
-				ScanMinIdleTime: time.Millisecond,
-				ScanMaxIdleTime: time.Millisecond,
 				Knobs: base.TestingKnobs{
 					Server: &server.TestingKnobs{
 						DefaultZoneConfigOverride: &zcfg,
@@ -1788,11 +1786,12 @@ func TestLargeUnsplittableRangeReplicate(t *testing.T) {
 
 	// We're going to create a table with many versions of a big row and a small
 	// row. We'll split the table in between the rows, to produce a large range
-	// and a small one. Then we'll increase the replication factor to 5 and check
-	// that both ranges behave the same - i.e. they both get up-replicated. For
-	// the purposes of this test we're only worried about the large one
-	// up-replicating, but we test the small one as a control so that we don't
-	// fool ourselves.
+	// and a small one. We'll also split the first row into its own range, to
+	// avoid the range inheriting 5 replicas from the system ranges. Then we'll
+	// increase the replication factor to 5 and check that both ranges behave the
+	// same - i.e. they both get up-replicated. For the purposes of this test
+	// we're only worried about the large one up-replicating, but we test the
+	// small one as a control so that we don't fool ourselves.
 
 	// Disable the queues so they don't mess with our manual relocation. We'll
 	// re-enable them later.
@@ -1805,6 +1804,8 @@ func TestLargeUnsplittableRangeReplicate(t *testing.T) {
 
 	_, err = db.Exec(`ALTER TABLE t EXPERIMENTAL_RELOCATE VALUES (ARRAY[1,2,3], 1)`)
 	require.NoError(t, err)
+	_, err = db.Exec(`ALTER TABLE t SPLIT AT VALUES (1)`)
+	require.NoError(t, err)
 	_, err = db.Exec(`ALTER TABLE t SPLIT AT VALUES (2)`)
 	require.NoError(t, err)
 
@@ -1862,7 +1863,7 @@ func TestLargeUnsplittableRangeReplicate(t *testing.T) {
 	testutils.SucceedsSoon(t, func() error {
 		forceProcess()
 		r := db.QueryRow(
-			"SELECT replicas FROM [SHOW RANGES FROM TABLE t] WHERE start_key LIKE '%TableMin%'")
+			"SELECT replicas FROM [SHOW RANGES FROM TABLE t] WHERE start_key LIKE '%/1'")
 		var repl string
 		if err := r.Scan(&repl); err != nil {
 			return err