This reverts commit 7c24ff2c.

Top level `pub` is being deprecated.

* Add new hook for setupHotReload and after updating devFS is complete

* Handle the case where updateDevFS failed

* Flutter_tools for web platform: report error messages with stacks on toolExit

Print error messages and stacks in verbose mode before calling
`throwToolExit` on communication errors to chrome and dwds.

This will help us disagnose CI flakes:

Helps: https://github.com/flutter/flutter/issues/84012
Closes: https://github.com/flutter/flutter/issues/87149

* Added tests

* Extend timeout for testing failure to connect to chrome

* Update rest of chrome tests to await until matching is finished

This changes the "Waiting for another flutter command to release the startup lock..." message output so that it appears on stderr instead of stdout. When it appears on stdout, it can mess up collection of the output. For instance, if you run flutter --version --machine and you're expecting JSON output, then you'll get non-JSON output even though the lock is released and you eventually would get what you're asking for.