PLT-3695 refactoring to use sql_upgrader (#3788)

* PLT-3695 unitying upgrade support

* PLT-3695 refactoring to use sql_upgrader

* Fixing unit test

* Adding 3.3 to 3.4

* Fixing upgrading

* Seperating DB schema from version.go

* Fixing upgrade cmd

* Moving to const for exit codes

* remving old unused code

store/sql_system_store.go

@@ -23,9 +23,6 @@ func NewSqlSystemStore(sqlStore *SqlStore) SystemStore {
 	return s
 }
 
-func (s SqlSystemStore) UpgradeSchemaIfNeeded() {
-}
-
 func (s SqlSystemStore) CreateIndexesIfNotExists() {
 }