migrations: Fix migration discrepancy on a system table.

Previously, the migration code for system table
`statement_diagnostics_requests` results in discrepancies when compared
to the table definition after bootstrapping. The discrepanies are
summarized in cockroachdb#77980.

This PR fixes it to ensure this table has exactly the same definition
after cluster upgrading as that from bootstrapping.

Release note (bug fix): Ensure the migration logic for
`system.statement_diagnostics_requests` results in a table definition
that is identical to that from bootstrapping.

Fixes: cockroachdb#77980

Sister Issue: cockroachdb#78302

pkg/migration/migrations/alter_statement_diagnostics_requests.go

@@ -26,14 +26,14 @@ import (
 const (
 	addColsToStmtDiagReqs = `
 ALTER TABLE system.statement_diagnostics_requests
-  ADD COLUMN min_execution_latency INTERVAL NULL,
-  ADD COLUMN expires_at TIMESTAMPTZ NULL`
+  ADD COLUMN min_execution_latency INTERVAL NULL FAMILY "primary",
+  ADD COLUMN expires_at TIMESTAMPTZ NULL FAMILY "primary"`
 
 	createCompletedIdxV2 = `
 CREATE INDEX completed_idx_v2 ON system.statement_diagnostics_requests (completed, ID)
   STORING (statement_fingerprint, min_execution_latency, expires_at)`
 
-	dropCompletedIdx = `DROP INDEX IF EXISTS completed_idx`
+	dropCompletedIdx = `DROP INDEX IF EXISTS system.statement_diagnostics_requests@completed_idx`
 )
 
 // alterSystemStmtDiagReqs changes the schema of the

pkg/migration/migrations/alter_statement_diagnostics_requests_test.go

@@ -62,6 +62,7 @@ func TestAlterSystemStmtDiagReqs(t *testing.T) {
 		validationSchemas = []migrations.Schema{
 			{Name: "min_execution_latency", ValidationFn: migrations.HasColumn},
 			{Name: "expires_at", ValidationFn: migrations.HasColumn},
+			{Name: "primary", ValidationFn: migrations.HasColumnFamily},
 		}
 	)