Set singleRun to true and remove from all karma start scripts

[dlarocque]

Enable singleRun once in the base Karma config instead of setting the flag in each of the karma scripts.

The test:debug scripts don't set --single-run, but I don't believe that enabling it should have any effect. If it needs to be disabled for these, we can set --no-single-run just for the debug scripts.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 29aa089

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[google-oss-bot]

Size Report ¹

Affected Products

No changes between base commit (3670ab8) and merge commit (0926e21).

Test Logs

• Base (3670ab8): https://github.com/firebase/firebase-js-sdk/actions/runs/10740973244
• Merge (0926e21): https://github.com/firebase/firebase-js-sdk/actions/runs/10743796931

1. https://storage.googleapis.com/firebase-sdk-metric-reports/z59FU30ByM.html

[google-oss-bot]

Size Analysis Report ¹

Affected Products

No changes between base commit (3670ab8) and merge commit (0926e21).

Test Logs

• Base (3670ab8): https://github.com/firebase/firebase-js-sdk/actions/runs/10740973244
• Merge (0926e21): https://github.com/firebase/firebase-js-sdk/actions/runs/10743796931

1. https://storage.googleapis.com/firebase-sdk-metric-reports/GHKaYL6XNq.html