Handle IR deletes

[arkodg]

Description:
With #404, the gateway-api translator now creates an IR per Gateway resource. This change in logic means that the gateway-api runner must also trigger an IR delete when a gateway resource has been deleted.

[arkodg]

one way to handle this would be

1. the runner would delete/reset all IR keys
2. repopulate with new keys
3. the infra and xds runner would subscribe for updates and not the complete state so can delete the translated ir resource based on delete notifications
4. must ensure 1) doesnt trigger multiple notifications and the end result of 2) is sent as a single notification

[arkodg]

hey @LukeShu is there a way to pause watchable notifications so interim loads and deletes dont trigger notifications or would we need to use an external mutex/condition variable construct.