Replaces timeline with quick action

Requires production!156 (merged)

This replaces the timeline section substitution with a quick action that is added to the incident template in production!156 (merged)

Part of https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/15890

Tested locally with https://gitlab.com/jarv/woodhouse-integration-test/-/issues/162

Additional refactor:

• Removes retryable loop for createIssue() since xanzy/go-gitlab does retrys
• In createIssue() we return immediately on any error