Show labels help message if last label is deleted

#### What does this PR do?

If the last label is deleted, the label information message is shown again

#### Why is this needed?

Currently, if the last label is delated, an empty white page is shown. UX is better, to show instructions for labels again.

#### Related issues

This is related to #7522 which implements the same for tags.
are you reloading page after each label remove action?