feat: DBTP-1507 Setup codepipeline notifications

[tony-griffin]

Addresses DBTP-1507

Use platform-helper notify commands for notifications, similar to our other pipelines.

---

Checklist:

Title:

• Scope included as per conventional commits
• Ticket reference included (unless it's a quick out of ticket thing)

Description:

• Link to ticket included (unless it's a quick out of ticket thing)
• Includes tests (or an explanation for why it doesn't)
• Includes any applicable changes to the documentation in this code base
• Includes link(s) to any applicable changes to the documentation in the DBT Platform Documentation (can be to a pull request)

Tasks:

• Trigger the pull request regression tests for this branch and confirm that they are passing

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 95.34884% with 2 lines in your changes missing coverage. Please review.

Project coverage is 81.56%. Comparing base (cbad429) to head (26d8ebf).

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...ipelines/custom_pipeline_update/update_pipeline.py	90.90%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #314      +/-   ##
==========================================
+ Coverage   80.83%   81.56%   +0.72%     
==========================================
  Files           5        7       +2     
  Lines         814      857      +43     
==========================================
+ Hits          658      699      +41     
- Misses        156      158       +2     

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