Move ping_appsec_on_approval.rb under appsec directory

What does this MR do and why?

Move ping_appsec_on_approval.rb under appsec directory

And cleanup some require.

Closes #965 (closed)

Expected impact & dry-runs

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Action items

• (If applicable) Add documentation to the handbook pages for Triage Operations =>
• (If applicable) Identify the affected groups and how to communicate to them:
  • /cc @person_or_group =>
  • Relevant Slack channels =>
  • Engineering week-in-review