fix(github-metrics): Default teams to be empty array

[hubertdeng123]

fixes https://sentry.sentry.io/issues/4517593692/?project=5246761&query=is%3Aunresolved&referrer=issue-stream&statsPeriod=24h&stream_index=0&utc=true
😬

[hubertdeng123]

I guess my dev schema I was testing with was slightly different than in prod, since mine was nullable...

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Files	Coverage Δ
src/utils/metrics.ts	76.64% <ø> (ø)

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[azaslavsky]

Approving this to unblock, but it doesn't seem like the schema changed anywhere? Is there anywhere that defines the common schema used in both test and prod? Put another way: I think this PR fixes the symptom (schema drift), but not the cause (there are separate schemas defined for prod and testing, making it very likely that they'll drift again).

[hubertdeng123]

I think a more permanent solution involves creating a dev BigQuery instance that is accessibly by everyone that is synced with the prod schema. Right now I'm using my own GCP project as a dev instance since I don't have access to the dev environment project that has been used in the past.

[hubertdeng123]

There is not a place where a common schema is used both in test and prod, but that'd be super nice to have.

Created an issue: #670