add print traces to reload isolate resume logic

[andrewkolos]

In service of #146879 and #145812.

This PR adds some more traces to help us figure out where we are getting blocked. See #146879 (comment) for more context.

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
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• I listed at least one issue that this PR fixes in the description above.
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• I added new tests to check the change I am making, or this PR is test-exempt.
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[jonahwilliams]

LGTM