Run e2e suite only if relevant contracts changed

[cam-schultz]

Context and scope
The separated e2e test suites introduced in #592 allow each suite to be run simultaneously and in isolation. However, the validator-manager suite in particular is long running, and it is unnecessary to run those tests if, say, a PR only changes the teleporter contracts.

Discussion and alternatives
We should separate the e2e jobs in the test workflow such that each suite only runs if files in the corresponding subdirectory of contracts are changed. We should still run all tests on merging to main.

The [paths](https://docs.github.com/en/actions/writing-workflows/workflow-syntax-for-github-actions#onpushpull_requestpull_request_targetpathspaths-ignore) syntax can be used to define these filters at the workflow level. Something like https://github.com/tj-actions/changed-files?tab=readme-ov-file can be used to do this at the job level.

Open questions
Questions that are still being discussed.