Backport executeaudited stable5

while the executeAudited() wrapper of OC_DB has become obsolete in master with the introduction of doctrine stable5 still needs to check the result of statement executions because MDB2 is used at runtime when running on oracle, not only during schema migration.

The first commit of this PR is not really a backport from master, but rather a cherry pick of https://github.com/owncloud/core/pull/3654 which made it into OC6 but was never backported to stable5.

The second commit uses executeAudited for all queries in the file cache. It makes debugging problems with the storage and cache parts of the filesystem a little bit less impossible. And I need that for a customer.

@DeepDiver1975 @icewind1991 @karlitschek