[BUGFIX] findByUid should respect query settings of repository

Prior to 6.1 findByUid built its own query which respected
the settings of its repository. Now findByUid just fetches
the object from the persistence manager which builds its own
query without respecting the query setting of the repository.

This leads to the error that the user isn't able to fetch
hidden records by uid any more. Therefore the
old behaviour of the repository must be used.
An according deprecation hint is added.

Releases: 6.2, 6.1
Resolves: #48571
Change-Id: Ic9a48d5d06f20b2ab8032c39eecb89cd52f898af
Reviewed-on: https://review.typo3.org/21385
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring