Currently users have to define the tag filters for repo mirroring even if they want to sync the entire repo with all its tags inside using the asterisk as a placeholder. Better UX would be that the tag filter field is an optional one and we automatically apply the asterisk if it's empty.

Acceptance criteria:

• UI should accept blank tags value which, upon save, will result in "*" wildcard shown.
• Side affect: Any blank tags entered will be converted to "*"