ISPN-3964 Move unstable tests to different group

* No tests are disabled. Unstable (random failing) tests should be
marked with group 'unstable'.  This can be applied to a class or
a method.
* Added profile test-unstable (-Ptest-unstable) to run only the
'unstable' group.
* Enabled all stress,profiling,manual tests since they do not run
automatically.
* Removed not implemented tests.
Move xsite random-failing tests to a separate group

They need to run on a single thread, unlike the core tests.
Fix some outdated tests.