Debugger `paused` event is sometimes not delivered to inspector client on macOS CI

[trivikr]

We have multiple macOS CI debugger flakes where the debuggee appears to pause, but the
inspector client process never observes the expected Debugger.paused event.

This has affected interactive debugger tests and probe mode. In probe mode, handlePaused()
should either record hits or resume unknown pauses. When the report has no hits and eventually
times out, the most likely signal is that the paused event never reached the inspector client
process.

The AI-assisted PRs have mostly tried to address nearby symptoms or test races, but they have
not resolved the underlying observation:

• debugger: defer probe pause handling until startup #63608 deferred probe pause handling until startup completed.
• debugger: avoid probe timeouts on target throws #63632 changed exception-pause behavior.
• test: fix debugger probe throwing getter flake #63944 adjusted a probe fixture to avoid missed startup breakpoints.
• test: wait for debugger pause state on startup #63968 changed tests to wait for paused state instead of pause-banner output.

Refs: #63632 (comment)

The question we need to answer is

Why is Debugger.paused sometimes never delivered to the inspector client process on macOS CI?

[joyeecheung]

I am not sure if we have another issue for this but the flake may have gone way back, it's been at least a year or two that debugger tests have been timing out on macOS GHA IIUC. The earliest attempt to fix it I could find was #60367 .

Also this appears to be GHA only, the debugger tests rarely timeout like this on macOS hosts on Jenkins

[github-actions]

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