fix: Spectre.CLI commands do not exit when pressing Ctrl + C

[philasmar]

Description of changes:
Since we are already detecting the Ctrl + C press and canceling the cancellation token, I just needed to exit the environment.

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Please upload report for BASE (feature/net8-upgrade@843a380). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
...AWS.Deploy.CLI/Commands/CancellableAsyncCommand.cs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@                   Coverage Diff                   @@
##             feature/net8-upgrade     #946   +/-   ##
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  Coverage                        ?   62.11%           
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  Files                           ?      294           
  Lines                           ?    10784           
  Branches                        ?     1612           
=======================================================
  Hits                            ?     6699           
  Misses                          ?     3488           
  Partials                        ?      597           

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