Add caching for AWS metadata

[lrafeei]

This PR adds the AWS metadata to the utilization class. This is for the specific case of when the agent is left continuously running and it is utilizing Kubernetes and AWS EC2 (but not EKS).

The utilization data is pulled the first time, but after this, the authentication token is unable to be refreshed. The utilization data will remain the same as long as the same agent instance, so if the EC2 instance fails, the agent will restart (and not just reconnect) and the utilization data will be fetched for the new EC2 instance.

[github-actions]

🦙 MegaLinter status: ✅ SUCCESS

Descriptor	Linter	Files	Fixed	Errors	Warnings	Elapsed time
✅ ACTION	actionlint	6		0	0	0.73s
✅ MARKDOWN	markdownlint	7	0	0	0	1.08s
✅ MARKDOWN	markdown-link-check	7		0	0	21.34s
✅ PYTHON	ruff	922	0	0	0	0.86s
✅ PYTHON	ruff-format	922	0	0	0	0.27s
✅ YAML	prettier	13	0	0	0	1.15s
✅ YAML	v8r	13		0	0	5.07s
✅ YAML	yamllint	13		0	0	0.59s

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 83.33333% with 2 lines in your changes missing coverage. Please review.

Project coverage is 81.36%. Comparing base (d4e359a) to head (ad22f14).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
newrelic/common/utilization.py	83.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1427      +/-   ##
==========================================
- Coverage   81.37%   81.36%   -0.02%     
==========================================
  Files         208      208              
  Lines       23543    23554      +11     
  Branches     3715     3716       +1     
==========================================
+ Hits        19158    19164       +6     
- Misses       3127     3130       +3     
- Partials     1258     1260       +2     

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[TimPansino]

What's the reasoning behind using environment variable to store this? Why not store it on the AWSUtilization class? (I think there's not an object for it but could still be stored on the class.) Or even store it in a global? What's the point of making it an env var we have to add to the customer's environment and then handle destroying on shutdown?