unsubscribe from webhook events that we don't actually handle

[matt-codecov]

github webhooks make up a huge portion of our incoming traffic, and a huge portion of our github webhooks don't have a handler defined so we just ignore them. there are no db queries involved when that happens, but it is still a lot of traffic

• (open on VPN) query showing volume of each unhandled webhook event
  • note that i double-counted this error until fix: stop double-counting unhandled_event in github webhook handler codecov-api#1140
• code where we select a handler / log that an event is unhandled

you can watch this dash (open on VPN) to see webhook volume and errors go down and this dash (open on VPN) to see total request volume go down

at time of writing the biggest culprits by far are:

• check_run
• check_suite
• create

there are many others:

• fork
• github_app_authorization
• issue_comment
• issues
• membership
• pull_request_review
• pull_request_review_comment
• pull_request_review_thread
• release
• team_add
• workflow_job
• workflow_run

assuming the app only sends webhooks to API and nowhere else, we should be able to nix all of those subscriptions and lower request volume

trent says if we need to add these subscriptions back later users won't need to reauthorize anything so there's no harm in dropping them now

[matt-codecov]

assigning to trent bc i don't have permissions to make the change