catfile: Fix ObjectReader not being dirty with in-use queue

In 21579e11 (catfile: Don't return readers to cache when their queues are in use, 2023-03-02), we have fixed a bug where both the object info and content reader were not considered dirty when their object queue was still in use. This caused us to return the readers back to the cache even though they might have still been in use.

Since then, we have introduced a new ObjectReader that combines both of these other types into one. Unfortunately though, it seems like the implementation was taken as an inspiration back when that bug still existed, which has the consequence that the same bug exists in this new type now.

Fix the bug by considering a reader to be dirty when its queue is in use.

Closes Object reader may be returned to the cache in d... (#5543 - closed).