backport search in shared files to stable5
OC5 does not have executeAudited
cleanup PR
- extract method,
- introduce MAX CHUNK SIZE const with 999 (reduce this by the number of additional query parameters),
- fix whitespace
fix placholder counting
Merge pull request #5487 from owncloud/backport_search_in_shared_files_to_stable5

backport search in shared files to stable5