feat: default cacheDirectory to TEST_TMPDIR

[sallustfire]

See #230

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Type of change

• New feature or functionality (change which adds functionality)

For changes visible to end-users

• Suggested release notes are provided below:

Now cacheDirector is set to TEST_TMPDIR by default to improve test isolation and cleanup.

Test plan

• This change is foundational and affects every test in the codebase. Existing tests confirm this doesn't introduce a regression.
• It doesn't appear to be possible to determine the cacheDirectory from within a jest test suite. However, an e2e test is added that explicitly sets --test_tmpdir and confirms that jest produced outputs in that folder indicating that it was successfully passed through the config chain.
• The case where user configuration specifies cacheDirectory via config is currently untested. It is unclear if that should even be allowed since --no-cache is forced and the location of the --cacheDirectory is otherwise an implementation detail of the rules.

[gregmagolan]

See https://bazelbuild.slack.com/archives/C04281DTLH0/p1706234301711269 for more context around this change.