Fix for #1605, only remove items that were selected for removal from the cache

[schuettecarsten]

Issue: #1605

PR Type

Only remove items that were selected for removal from the cache

[X] Bugfix
[ ] Feature
[ ] Code style update (formatting)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build or CI related changes
[ ] Documentation content changes
[ ] Sample app changes
[ ] Other... Please describe:

PR Checklist

Please check if your PR fulfills the following requirements:

• Tested code with current supported SDKs
• Docs have been added / updated (for bug fixes / features)
• Sample in sample app has been added / updated (for bug fixes / features)
• Tests for the changes have been added (for bug fixes / features) (if applicable)

Does this PR introduce a breaking change?

[ ] Yes
[X] No

Other information

I found this issue while using the Cache in our app. Unfortunately, I was not yet able to run, adjust or fix any of the UWP-toolkit tests, because I ran out of time at the moment. Sorry 4 that!

[windowstoolkitbot]

This PR is linked to unclosed issues. Please check if one of these issues should be closed: #1605