Update e2e tests to only run on PRs with changes to the codebase

[seantking]

Summary

At the moment we run the e2e tests on every PR. For example, this PR only contains a change to a README.md.

We should probably just run the e2e tests for changes to the core codebase.

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[chatton]

this is a great idea and should definitely be done. We can get a long way by extending the paths-to-ignore option in all e2e workflows.

  paths-ignore:
    - docs/**
    - **.md

[chatton]

Reopening as the fix did not work as I expected, this is still happening. See this pr which only changes .MD files