Add Python Version Input Option for EC2

[harrryr]

Issue description:
Updating Python EC2 to have input option for language version.

Description of changes:

• Update Python sample app dependency versions to be compatible with Python 3.8
• Python 3.8, 3.10, 3.12 isn't available through dnf/yum. Therefore, manually build and install python by downloading source code.
• Setting default version to 3.9 since downloading through dnf is faster than manually installing it. (It was also the version already being used by ec2 tests)

Rollback procedure:
Revert

Test run: https://github.com/harrryr/aws-application-signals-test-framework/actions/runs/11157966893

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