Calling didContinue() after having paused on an instrumentation break
clears the breakpoint reasons that were stored in the debugger agent.

This removes clearBreakDetails() from didContinue() and specifically
calls it if we need it.

Drive-by: removing left-over dead code

Bug: chromium:1229541
Change-Id: I49f598d0e97801661e003c3911967c64ea63373e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3477099Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Kim-Anh Tran <kimanh@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79203}