UserStore migration (#15563)

* Migration completed

* Fix tests

* Fix tests

* Fix tests

* Suggestions

* Trigger CI

* Suggestions

* Merge with master

* Trigger CI

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>
Co-authored-by: Agniva De Sarker <agnivade@yahoo.co.in>

store/constants.go

@@ -6,9 +6,6 @@ package store
 const (
 	CHANNEL_EXISTS_ERROR = "store.sql_channel.save_channel.exists.app_error"
 
-	MISSING_ACCOUNT_ERROR      = "store.sql_user.missing_account.const"
-	MISSING_AUTH_ACCOUNT_ERROR = "store.sql_user.get_by_auth.missing_account.app_error"
-
 	USER_SEARCH_OPTION_NAMES_ONLY              = "names_only"
 	USER_SEARCH_OPTION_NAMES_ONLY_NO_FULL_NAME = "names_only_no_full_name"
 	USER_SEARCH_OPTION_ALL_NO_FULL_NAME        = "all_no_full_name"