[integ-tests-framework] Add Cache to Retrieve Instance Types to Speed Up Integration Test Setup

[hanwen-cluster]

Description of changes

The describe_instance_type_offerings call has a huge response body, therefore taking long. Adding a cache to the function to reduce the numer of the API call. This speed up integration test framework startup time by 5 minutes

Tests

• Test the setup phase with develop.yaml, and verified all Jinja variables in develop.yaml are rendered correctly.

References

• This is a improvement on [integ-test] rotate instance types for some integration tests #6645

Checklist

• Make sure you are pointing to the right branch.
• If you're creating a patch for a branch other than develop add the branch name as prefix in the PR title (e.g. [release-3.6]).
• Check all commits' messages are clear, describing what and why vs how.
• Make sure to have added unit tests or integration tests to cover the new/modified code.
• Check if documentation is impacted by this change.

Please review the guidelines for contributing and Pull Request Instructions.

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