Download Enablement Script from Github Repo Instead of S3

[harrryr]

Issue #, if available:
The latest scripts for App Signals Enablement are now located in this repo.

Description of changes:
Replace the code downloading the enablement scripts from the S3 Bucket and download the scripts directly from the github repository instead.

Also remove the change ADOT image if main-build step, outdated code.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (f5fc3b3) 50.73% compared to head (7b47778) 50.73%.
Report is 2 commits behind head on main.

❗ Current head 7b47778 differs from pull request most recent head 3cb11b2. Consider uploading reports for the commit 3cb11b2 to get more accurate results

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Additional details and impacted files

@@            Coverage Diff            @@
##               main     #655   +/-   ##
=========================================
  Coverage     50.73%   50.73%           
  Complexity      264      264           
=========================================
  Files            39       39           
  Lines          1301     1301           
  Branches        141      141           
=========================================
  Hits            660      660           
  Misses          609      609           
  Partials         32       32           

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[majanjua-amzn]

Can we do a test run?