fix: small fixes for the meta DB

[betodealmeida]

SUMMARY

• table.count() was not working with BigQuery, I switched to a more generic idiom.
• When inserting null values, remove them from any columns with autoincrement (otherwise apsw will complain).

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API