RFR: 6960970: Debugger very slow during stepping [v8]

[Serguei Spitsyn]

> This change fixes a long standing performance issue related to the debugger single stepping that is using JVMTI `FramePop` events as a part of step over handling. The performance issue is that the target thread continues its execution in very slow `interp-only` mode in a context of frame marked for `FramePop` notification with the JVMTI `NotifyFramePop`. It includes other method calls recursively upon a return from the frame.
> 
> This fix is to avoid enforcing the `interp-only` execution mode for threads when `FramePop` events are enabled with the JVMTI `SetEventNotificationMode()`. Instead, the target frame has been deoptimized and kept interpreted by disabling `OSR` optimization by the function `InterpreterRuntime::frequency_counter_overflow_inner()`. (Big thanks to @fisk for this suggestion!) Additionally, some tweaks are applied in several places where the `java_thread->is_interp_only_mode()` is checked.
> The other details will be provided in the first PR request comment.
> 
> Testing:
>  - test `serviceability/jvmti/vthread/ThreadStateTest` was updated to provide some extra test coverage
>  - submitted mach5 tiers 1-6

Serguei Spitsyn has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains nine commits:

 - merge: fix merge error
 - Merge
 - Merge
 - review: optimize hide_single_stepping and post_method_exit
 - review: renamed two functions; FRAME_POP_BIT removed from INTERP_EVENT_BITS
 - review: fix iteration order in process_vthread_pending_deopts as it uses remove_at(idx)
 - review: fix typo in a EATests.java comment
 - cleanup: removed an old code fragment in frame.cpp
 - 6960970: Debugger very slow during stepping

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Changes: https://git.openjdk.org/jdk/pull/28407/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28407&range=07
  Stats: 255 lines in 22 files changed: 158 ins; 61 del; 36 mod
  Patch: https://git.openjdk.org/jdk/pull/28407.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28407/head:pull/28407

PR: https://git.openjdk.org/jdk/pull/28407