change: Remove throw from local task cancellation

[shpface]

Issue #, if available:

Description of changes: Cancellation of AWS tasks is a best effort process. Attempting to cancel an AWS task which has already completed is not an error. This change will make local tasks behave the same way.

Testing done:

Merge Checklist

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General

• [x] I have read the CONTRIBUTING doc
• [x] I used the commit message format described in CONTRIBUTING
• [x] I have updated any necessary documentation, including READMEs and API docs (if appropriate)

Tests

• [x] I have added tests that prove my fix is effective or that my feature works (if appropriate)
• [x] I have checked that my tests are not configured for a specific region or account (if appropriate)

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[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 100.00%. Comparing base (a76c4e2) to head (2891022). :warning: Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #856   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files          162       162           
  Lines        10450     10452    +2     
  Branches      1296      1296           
=========================================
+ Hits         10450     10452    +2     

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