test: RelocationTests.testCancellationCleansTempFiles may fail due to io errors while check temp files are deleted

Windows can throw NoSuchFileException when using File.walkFileTree and deleting files concurrently. This commit changes IO exceptions into assertion error so that assertBusy will wait for them as well.
[UTILITIES] Introduce a RefCounted interface and basic impl

We already have two places duplicating this rather hairy logic, this
commit intorduces a new RefCoutned interace and an abstract implementation
that can be used for delegation. It factors out all the reference counting
and adds single and multithreaded test for it.

Closes #8210
[CACHE] Expose concurrency_level on all caches

The concurrency level allows to configure the cache internal segments
used to cache data. This can have direct impact on evicition rates since
memory bound caches are equally divided into segments which can cause
early evictions if cache entries are not well balanced.

Relates to #7836
[STORE] Don't catch FNF/NSF exception when reading metadata

When reading metadata we do catch FileNotFound and NoSuchFileExceptions
today, log the even and return an empty metadata object. Yet, in some cases
this might be the wrong thing todo ie. if a commit point is provided these
situations are actually an error and should be rethrown. This commit
pushes the responsiblity to the caller to handle this exception.

Closes #8207