Disable daily maintenance with transactions

The daily maintenance worker does not use a transaction and accesses repositories directly. It thus conflicts with the work TransactionManager is doing.

Changing daily maintenance to work with transactions is not worth it. We need to pack the repositories actively as they are written to since the file count impacts snapshotting efficiency. TransactionManager sees all changes and thus can trigger the maintenance when it is needed. Random daily walk is not useful in this context as Gitaly no longer leaves garbage in the repositories. The garbage left over by failures get cleaned up with the transactions.

This MR disables daily maintenance when transactions are enabled.

Closes #5782 (closed)