Moves TestIsolation from enterprise to kernel and renames it, as well as the original TestIsolation

Moves the enterprise TestIsolation test to community, since it has no relation to HA or enterprise
 specific functionality. Also renames it to TestIsolationMultipleThreads to separate it from the
 other isolation test.
Renames the original TestIsolation to TestIsolationBasic since it tests the most rudimentary
 isolation guarantees.

Finally, Ignores the TestIsolationMultipleThreads since it is flaky (it was recently re-enabled).