Fix #81585: Reused cached_chunks are not counted to heap size

[cmb69]

Whenever we reuse or delete a cached_chunk, we need to adjust the
memory stats like we do when allocating or deleting a non cached chunk.

[cmb69]

@dstogov, do you see any issues with this fix?

[dstogov]

Zend MM keeps in real_size the amount of allocated system memory. This includes the allocated cached pages, as we don't return them to system. This counting was done on purpose. Accurate information about memory used by PHP application is available in size.

I don't see a big reason to change this.

[cmb69]

Thanks for the explanation, @dstogov. And of course, you're right! I'll come up with another PR which does not change real_size.