Remove Error Tracking Feature Flags

Everyone can contribute. Help move this issue forward while earning points, leveling up and collecting rewards.

• Work on this issue
• Close this issue

Definition of done

• Remove integrated_error_tracking feature flag
• Remove gitlab_error_tracking feature flag

Implementation plan

These flags are both enabled for GitLab.com now, but are default disabled for self-managed so we can't just remove the flags entirely. We might need to refactor it as a SaaS-only feature: https://docs.gitlab.com/ee/development/ee_features.html#saas-only-feature

Addresses concerns raised in gitlab-org/quality/triage-reports#20990 (closed)