Convert unique keys in 3 tables to primary keys (#115421)

* Added method for adding migrations for convering unique to primary key.

Based on existing migration for `file` table (in `db_file_storage.go`) migrations.

* Added better default migration names. Added ability to override migration name.

* Use ConvertUniqueKeyToPrimaryKey for cloud_migration_snapshot_partition table.

* Convert resource_version UQE to PK.

* Convert secret_encrypted_value UQE to PK.

* Removed extra test.

* Removed testdata.

* Remove support for renaming migrations for now. We can bring it in later, when we want to convert existing migrations for file, file_meta and setting tables.

* Revert removal of ColumnName to ease backporting, since this field is referenced from enterprise code.

* Use quoted identifiers in Postgres statement.

pkg/services/sqlstore/migrator/migrator.go

@@ -8,7 +8,6 @@ import (
 
 	_ "github.com/go-sql-driver/mysql"
 	"github.com/golang-migrate/migrate/v4/database"
-	"github.com/grafana/grafana/pkg/util/sqlite"
 	_ "github.com/lib/pq"
 	"github.com/prometheus/client_golang/prometheus"
 	"go.opentelemetry.io/otel"
@@ -17,6 +16,8 @@ import (
 	"go.opentelemetry.io/otel/trace"
 	"go.uber.org/atomic"
 
+	"github.com/grafana/grafana/pkg/util/sqlite"
+
 	"github.com/grafana/grafana/pkg/util/xorm"
 
 	"github.com/grafana/grafana/pkg/infra/log"
@@ -67,12 +68,16 @@ func NewMigrator(engine *xorm.Engine, cfg *setting.Cfg) *Migrator {
 
 // NewScopedMigrator should only be used for the transition to a new storage engine
 func NewScopedMigrator(engine *xorm.Engine, cfg *setting.Cfg, scope string) *Migrator {
+	return newMigrator(engine, cfg, scope, NewDialect(engine.DriverName()))
+}
+
+func newMigrator(engine *xorm.Engine, cfg *setting.Cfg, scope string, dialect Dialect) *Migrator {
 	mg := &Migrator{
 		Cfg:          cfg,
 		DBEngine:     engine,
 		migrations:   make([]Migration, 0),
 		migrationIds: make(map[string]struct{}),
-		Dialect:      NewDialect(engine.DriverName()),
+		Dialect:      dialect,
 		metrics: migratorMetrics{
 			migCount: prometheus.NewCounterVec(prometheus.CounterOpts{
 				Namespace: "grafana_database",