chore: set exit code to 1 on test failures

[galargh]

• Because this PR includes a bug fix, relevant tests have been included.
• Because this PR includes a new feature, the change was previously discussed on an Issue or with someone from the team.
• I didn't do anything of this.

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This is a follow-up to the discussions in #5584 (comment) and https://nomicfoundation.slack.com/archives/C05MKFQJBCH/p1724801183793089?thread_ts=1724682710.005219&cid=C05MKFQJBCH

This PR ensures that both node:test and mocha test runner plugins set the process exit code to 1 instead of a number of failures when they encounter test failures. This ensures our exit code usage is along what's commonly expected, e.g. https://tldp.org/LDP/abs/html/exitcodes.html

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