fix: Refactor repack_model script injection, fixes tar.gz error

[staubhp]

…gz error

Issue #, if available:
3038

Description of changes:
Repack model injection is not working for S3 source directories. Refactor this to follow logic similar to Model's repack method.

Testing done:
Manual, unit

Merge Checklist

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General

• I have read the CONTRIBUTING doc
• I certify that the changes I am introducing will be backword compatible, and I have discussed concerns about this, if any, with the Python SDK team
• I used the commit message format described in CONTRIBUTING
• I have passed the region in to all S3 and STS clients that I've initialized as part of this change.
• I have updated any necessary documentation, including READMEs and API docs (if appropriate)

Tests

• I have added tests that prove my fix is effective or that my feature works (if appropriate)
• I have added unit and/or integration tests as appropriate to ensure backward compatibility of the changes
• I have checked that my tests are not configured for a specific region or account (if appropriate)
• I have used unique_name_from_base to create resource names in integ tests (if appropriate)

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[sagemaker-bot]

AWS CodeBuild CI Report

• CodeBuild project: sagemaker-python-sdk-unit-tests
• Commit ID: 6b517c5
• Result: SUCCEEDED
• Build Logs (available for 30 days)

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[sagemaker-bot]

AWS CodeBuild CI Report

• CodeBuild project: sagemaker-python-sdk-local-mode-tests
• Commit ID: 6b517c5
• Result: SUCCEEDED
• Build Logs (available for 30 days)

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[codecov-commenter]

Codecov Report

Merging #3039 (6b517c5) into master (8e0a37f) will increase coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #3039      +/-   ##
==========================================
+ Coverage   89.33%   89.39%   +0.05%     
==========================================
  Files         196      196              
  Lines       16649    16650       +1     
==========================================
+ Hits        14874    14884      +10     
+ Misses       1775     1766       -9     

Impacted Files	Coverage Δ
src/sagemaker/workflow/_utils.py	95.83% <100.00%> (+8.43%)	⬆️
src/sagemaker/session.py	70.44% <0.00%> (-0.08%)	⬇️

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