fix(ingest) bigquery: Moving bigquery temporary credential deletion to atexit

[treff7es]

Moving bigquery temporary credential deletion to atexit vs del because it is more reliable and deterministic.
Recently with del it threw an error because the logging object was None as it seemed to be cleaned up when the method was called.

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable). If a new feature has been added a Usage Guide has been added for the same.
• For any breaking change/potential downtime/deprecation/big changes an entry has been made in Updating DataHub

[github-actions]

Unit Test Results (build & test)

  97 files  ±0    97 suites  ±0   17m 25s ⏱️ - 2m 47s
701 tests ±0  642 ✔️ ±0  59 💤 ±0  0 ❌ ±0 

Results for commit 5259b17. ± Comparison against base commit f659cc8.

♻️ This comment has been updated with latest results.

[github-actions]

Unit Test Results (metadata ingestion)

       5 files         5 suites   1h 3m 58s ⏱️
   431 tests    431 ✔️   0 💤 0 ❌
2 080 runs  2 014 ✔️ 66 💤 0 ❌

Results for commit 5259b17.

♻️ This comment has been updated with latest results.

[rslanka]

LGTM!