[server][hotfix] Disable webhooks for github.com and GitHub Enterprise

[jankeromnes]

Description

Very partial revert of #8574

Related Issue(s)

Hopefully fixes #8719

How to test

Already deployed in production as a hotfix to server pods

Release Notes

NONE

Documentation

[codecov]

Codecov Report

Merging #8722 (45ffc24) into main (a9715ee) will decrease coverage by 1.13%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #8722      +/-   ##
==========================================
- Coverage   12.31%   11.17%   -1.14%     
==========================================
  Files          20       18       -2     
  Lines        1161      993     -168     
==========================================
- Hits          143      111      -32     
+ Misses       1014      880     -134     
+ Partials        4        2       -2     

Flag	Coverage Δ
components-gitpod-cli-app	11.17% <ø> (ø)
components-local-app-app-darwin-amd64	?
components-local-app-app-darwin-arm64	?
components-local-app-app-linux-amd64	?
components-local-app-app-linux-arm64	?
components-local-app-app-windows-386	?
components-local-app-app-windows-amd64	?
components-local-app-app-windows-arm64	?

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Impacted Files	Coverage Δ
components/local-app/pkg/auth/pkce.go
components/local-app/pkg/auth/auth.go

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[JanKoehnlein]

LGTM