DWDS should not send a `resume` event after a hot-restart

DWDS sends a `resume` event after a hot-restart, which is inconsistent with the behavior of the VM Service.

Details below are copied from: https://github.com/flutter/devtools/pull/9125

* Here is where the `resumeFromStart` method (which calls the `_resumeHandler` which sends the `Resume` event) was added:
https://github.com/dart-lang/webdev/pull/636

* And here is where it began to be called in response to "creating a new isolate" (which is not a real isolate since there are no isolates on web) and occurs in response to a hot-restart:
https://github.com/dart-lang/webdev/pull/747

(For reference, current code pointers here: https://github.com/flutter/devtools/issues/9124#issuecomment-2791151431)

Trace the resumeFromStart method and its _resumeHandler, using the linked webdev pull requests and current code pointers as the starting points. Reproduce or inspect the hot-restart path where a new web isolate is created, then verify that hot-restart no longer emits a resume event while normal VM Service behavior remains consistent.

Written by the indexing model from the issue text.