Address the Primary Key Overflow risk for the ci_builds_runner_session table - Step 3: Drop temporary columns and triggers

Instead of creating issues for each step, the work for the steps is outlined below. An MR will be created for each of the steps.

• Step 3.1:
  • Ignore column build_id_convert_to_bigint (ensure there are no other columns to additionally ignore)
  • Drop trigger to keep columns in sync
• Step 3.2: Dropping the column (release m+1) - build_id_convert_to_bigint
• Step 3.3: Removing the ignore rule (release m+2)