fix(AppConfig): Updated AppConfig boto3 Client Timeout

[CoshUS]

Description of changes:
boto3 client has default 60 seconds timeout for both read and connection.
The worst case would be 360 seconds from 120 seconds timeout * 3 retires.
SAM translator lambda function has 120 seconds timeout which can be exceeded if AppConfig experiences a long response delay issue.

Description of how you validated changes:
Tested with 900ms network latency. (1800ms roundt trip)

Checklist:

• Write/update tests
• make pr passes
• Update documentation
• Verify transformed template deploys and application functions as expected

Examples?

Please reach out in the comments, if you want to add an example. Examples will be
added to sam init through https://github.com/awslabs/aws-sam-cli-app-templates/

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

[codecov-io]

Codecov Report

Merging #1870 (88f2759) into develop (f97cdda) will increase coverage by 0.05%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop    #1870      +/-   ##
===========================================
+ Coverage    93.97%   94.02%   +0.05%     
===========================================
  Files           89       89              
  Lines         5826     5828       +2     
  Branches      1185     1185              
===========================================
+ Hits          5475     5480       +5     
+ Misses         162      160       -2     
+ Partials       189      188       -1     

Impacted Files	Coverage Δ
samtranslator/feature_toggle/feature_toggle.py	87.50% <100.00%> (+0.35%)	⬆️
samtranslator/translator/logical_id_generator.py	100.00% <0.00%> (+9.09%)	⬆️

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