Set eslint's max-warnings to 0 to match pre-commit hooks

[reggieriser]

Description

We had some code that had eslint warnings slip into master (see Slack thread for more context). Those warnings started to show up on subsequent PRs. Digging into how this could get through our checks, I noticed our pre-commit hooks set --max-warnings=0 on eslint which fails the hook if there are warnings (the warnings got in by accident after disabling pre-commit hooks to get code pushed up). In contrast, the eslint command we use in the build process did not have max-warnings set. This adds it.

Reviewer Notes

This PR should have some failures until we get the warnings fixed. I wanted to get a PR up and make sure that it failed on warnings, then we can merge the warning fixes in when they land and try it again and see that everything is hopefully clear. I don't want to merge this until we're clear as it may block the warning fixes from being applied. I'll make this a draft PR and label it with do not merge until everything's ready. Update: PR is now out of draft and warnings should be gone.

Let me know if you can think of anything that this would negatively impact.

Setup

Locally, you can run yarn run lint and see that the warnings return an exit code of 1 now. You should hopefully see a failure in the checks on this PR too.

[reggieriser]

Just capturing screenshots of the failures while the warnings are still in the branch.

[gidjin]

LGTM, probably need to resolve the warnings before merging though

[reggieriser]

LGTM, probably need to resolve the warnings before merging though

That was the plan -- see the reviewer's notes. I was just waiting for #7618 to land. Thanks for the review.

[robot-mymove]

	Warnings
⚠️	Changes were made to package.json, but not to yarn.lock - Perhaps you need to run yarn install?
⚠️	Please add the JIRA issue key to the PR title (e.g. MB-123)

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