Fix failing checks: e2e tests, welcome action

[becky-gilbert]

This PR fixes some bugs in the e2e tests and results page:

e2e/experiment.test.js

• Incorrect URL was used in the API mock (should be **/api/${expInfo.shortName}/getPercentileRank instead of **/api/results).
• Removed test for "Loading..." text - this state is too brief to test reliably.
• Mocked API response was returning the results in an incorrect format - needs to be wrapped in a resData object.
• API mock needs to be set up before the page click, so that it catches the request (no reload needed).

e2e/results.test.js

• In the beforeEach, use page.waitForResponse to make sure that the API post request has finished before checking results. Previously this was just using the DOM content to check that the results are ready, but the POST request and database update could still have been pending, which was causing intermittent errors.

templates/experiments/[EXP]/src/web page/src/results.js

• Fix logic error that determines whether the page should show the "Oops! Something went wrong" message. The previous logic used a falsy check for data.percentileRank and data.summary_stat, so when those values were 0 (valid), it produced the error message. Now it checks for null/undefined. (I didn't change the falsy !data.totalRows check. A value of 0 is valid, but that case is handled earlier - it produces a "Results aren't available" message). This issue was causing one of the e2e tests to fail.

This also fixes some bugs in the failing 'welcome' Github Workflow: .github/workflows/welcome.yml

• The actions/first-interaction action updated its API to use underscores, but the config was still using the old hyphenated names.
• Removes the unnecessary actions/checkout@v3 step. The actions/first-interaction only needs the GitHub token to post a comment, not the repository contents, and the repo cloning step takes a very long time.
• Adds a manual dispatch option to the welcome action, for easier testing (this action only runs on newly-opened PRs/issues, which makes it hard to test changes).

[changeset-bot]

🦋 Changeset detected

Latest commit: 15ad62a

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

Name	Type
@pushkin-templates/exp-basic	Patch
@pushkin-templates/exp-grammaticality-judgment	Patch
@pushkin-templates/exp-lexical-decision	Patch
@pushkin-templates/exp-self-paced-reading	Patch

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[becky-gilbert]

@cherriechang do you mind reviewing this? All of the fixes were in test files or GH action config, so it shouldn't conflict with anything that you're working on. The only exception is this change to the templates/experiments/[exp]/src/web page/src/results.js files: 58c32b7 which was causing incorrect results page content when the percentile rank or summary stat is a valid 0 value. We could revert that commit here if you've already addressed that issue somewhere else.

[cherriechang]

This looks good, thank you!! Everything makes sense and was easy to follow from the PR conversation.