fix(dav): dav:remove-invalid-shares removing federated calendar shares

[st3iny]

• Resolves: none

Summary

The command removes valid federated calendar shares as it is not able to find remote user principals.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

[st3iny]

/backport to stable32

[st3iny]

Tests are indeed broken due to my changes. I'm on it.

[github-actions]

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