chore(migrations): Renaming migration files so that they're easier to keep track of (#20284)

* Renaming migration files so that they're easier to keep track of

* Fixing broken import

* Fixing broken import again

* Fixing broken tests

superset/migrations/alembic.ini

@@ -19,7 +19,7 @@
 
 [alembic]
 # template used to generate migration files
-# file_template = %%(rev)s_%%(slug)s
+file_template = %%(year)d-%%(month).2d-%%(day).2d_%%(hour).2d-%%(minute).2d_%%(rev)s_%%(slug)s
 
 # set to 'true' to run the environment during
 # the 'revision' command, regardless of autogenerate