oc-avatar shifts layout after loading

[PVince81]

Steps

1. Create two users "user1" and "user2" without avatars
2. Login as "user1"
3. Open the collaborators panel for any resource
4. Add a new collaborator
5. Type "us" and observe closely the avatar in the autocomplete dropdown
6. Select "user2" and confirm
7. Open the collaborators panel again and observe closely the avatar in the collaborators list

Expected result

• Only one spinner in place of the avatar while loading.
• After the avatar placeholder appears, the layout must stay in place

Actual result

• Two spinners appear above each other in place of the avatar
• After the avatar placeholder appears, the layout is shifting slightly

Note that some random test failures exist in CI with the "iPhone" form factor as sometimes the avatar load timing is different and the container layout shifts before the test runner can click on a selected element.

Version

Phoenix master e0df137

It is possible that the issue is related to the component in ODS, but is not confirmed yet as ODS doesn't provide an example of the spinner.

@kulmann as discussed.

[PVince81]

PR here: #2927