feat(Gong) - add an optional retention policy

[aubin-tchoi]

Description

This PR implements an optional retention policy.

• When disabled, all transcripts are synced (no change here).
• When enabled, only the transcripts that are no older than the retention period are synced.

This behavior is implemented using two things:

• We fetch transcripts starting from the retention period at minimum.
• We garbage collect outdated transcripts.

Tests

• Ongoing.

Risk

• N/A.

Deploy Plan

• Apply migration_62.sql.
• Deploy connectors.

[github-actions]

	Warnings
⚠️	Files in **/lib/models/ have been modified and the PR has the migration-ack label. Don't forget to run the migration from prodbox.

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