Integration hooks loading more frequently than necessary

This issue came out of this discussion &7290 (comment 1175265005).

Problem

Nearly all hook event properties are default set to true for all integrations regardless of whether the integration uses the hooks or not.

Only integrations that specifically allow people to check and uncheck the hook event options in the integration form can have false values for some events (limited to integrations that inherit from BaseChatNotification only).

The integration models themselves implement a .supported_events method that specifies whether they support the events, but that is checked later at the point where we have loaded the record and attempted to execute it.

The unfortunate result of this is that the Project#has_active_integrations? check is much less helpful in terms of a performance optimisation made before attempting to evaluate data payloads or execute integration hooks, as projects with any enabled integrations will generally report true even when it's not.

We're likely to be loading integrations very frequently, and building data payloads, which ultimately are all for nothing.

This will lead to many unnecessary PostgreSQL queries.

Proposal

1. Integrations should always set event properties that don't correlate to the model's .supported_events to false.
2. Add a data migration to correct existing data.