[stable32] fix: calendar subscription memory exhaustion

[backportbot[bot]]

Backport of #56784

Warning, This backport's changes differ from the original and might be incomplete ⚠️

Todo

• [x] Review and resolve any conflicts
• [x] Amend HEAD commit to remove the line stating to skip CI

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[SebastianKrupinski]

Fixed conflict in CalDAVBackend::getLimitedCalendarObjects