SDCICD-1411 add ability to alternate between two aws accounts

[ritmun]

SDCICD-1411 add ability to alternate between two aws accounts when AWS_SHARED_CREDENTIALS are provided in env var

• AWSSharedCredentials is the base64 encoded AWS credentials file content.

• Variable should contain two named profiles: "profile-a" and "profile-b" If provided, supersedes AWS secret set in env.

• This is used to optimize AWS resource spending by nuking each of the 2 accounts alternately.

• Since simply checking whether current week is odd or even within current year may result in unexpected outage if a year has odd number of weeks, use odd/even based on a constant start date.

[ritmun]

I'll squash all commits manually when review is done

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jbpratt, ritmun

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/openshift/osde2e/blob/main/OWNERS)~~ [jbpratt,ritmun] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[openshift-ci[bot]]

@ritmun: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/hypershift-pr-check	88810605fa9227dd9e0a7054d1f0eb339e46ee35	link	false	/test hypershift-pr-check

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