Denormalize event type for request and event logs

[ezekg]

Part 1 of 4. Improves performance for Dashboard metrics.

Prerequisites

• Cut new Keygen CE/EE versions so we release multi-user licenses before this.

Post deploy

Part 2 (in order of operations)

• Backfill denormalized event_type_event from event_types to event_logs.
• Add NOT NULL constraint to event_logs.event_type_event.
• Add index on event_logs.event_type_event.
• Run VACUUM ANALYZE event_logs.

Part 3 (in order of operations)

• Backfill denormalized event_type_id and event_type_event from event_logs to request_logs.
• Add NOT NULL constraints to request_logs.event_type_id and request_logs.event_type_event.
• Add indexes on request_logs.event_type_id and request_logs.event_type_event.
• Run VACUUM ANALYZE request_logs.

Part 4

• Update EventLog.for_event_type to use denormalized event_type_event column for strings.
• Update RequestLog.for_event_type to use denormalized event_type_event column.