It is to fix#3185.
This fixes the case where MetaDB is not instantiated (none of the conditions match),
and we want to retain tags only by pattern (which should not need to use MetaBD).
Without this fix you could only use retention to delete untagged manifests.
If you specified only the key "patterns" under "keepTags", zot would crash.
It was possible to not specify "keepTags" all, which would retain all tags,
but it was not possible to retains specific tags.
Basically the case quoted below, from the documentation, was broken::
https://zotregistry.dev/v2.1.4/articles/retention/#configuration-example
```
When you specify a regex pattern with no rules other than the default, all tags matching the pattern are retained.
```
This would only work if MetaDb was instantiated by an unrelated configured feature.
Signed-off-by: Andrei Aaron <aaaron@luxoft.com>
wait for workers to finish before exiting
should fix tests reporting they couldn't remove rootDir because it's being
written by tasks
Signed-off-by: Petu Eusebiu <peusebiu@cisco.com>
Andrei Aaron