Fix ThreadScheduler and ThreadState state machine logic

[eupp]

Currently the Lincheck strategies classes use the following ThreadState state machine to manage the threads:

lincheck/src/jvm/main/org/jetbrains/kotlinx/lincheck/strategy/ThreadScheduler.kt

Line 35 in a758c54

* Here is a state diagram of the thread life cycle in Lincheck:

However, currently there are several technical problems in the code base:

• Analysis code injections can be invoked even if the thread is in aborted state --- we should instead exit injected code as early as possible in this case.
• onThreadFinish injection in ManagedStrategy assumes the code runs in "managed" mode, that is one thread is run at a time --- but this is not true in the aborted state. Therefore the transition from aborted to finished state is not implemented properly, and the thread may end up in Aborted state instead of Finished state after thread termination.