pipeline testing for azure-ipam/cni-dropgz submodules

[camrynl]

Reason for Change:

Current state of e2e tests changes to dropgz/azure-ipam on every run regardless of whether or not change is present. Adding submodule pipeline that will only trigger runs if there are changes in the azure-ipam or dropgz directories. This pipeline will test the cni-dropgz-test image.
When changes are not present, the e2e tests will run only on the regular cni-dropgz image, which is built from the cni installer that utilizes released versions of components.

New Submodule Pipeline: https://dev.azure.com/msazure/One/_build?definitionId=292133&_a=summary

Issue Fixed:

Requirements:

• [ ] uses conventional commit messages
• [ ] includes documentation
• [ ] adds unit tests

Notes:

[camrynl]

validated pipeline tests via manual run: https://dev.azure.com/msazure/One/_build/results?buildId=61311663&view=results

unable to run the full submodule pipeline via PR trigger since submodules-pipeline.yaml is not merged to master and does not have access to pipeline secrets (for Docker login)

Only testing ipam/dropgz against swifte2e and ciliume2e scenarios. Is there anything else we want to include/exclude in the pipeline? @rbtr

[camrynl]

• enabled access of pipeline secrets to forks in repo and validated the new submodule pipeline with PR trigger: https://dev.azure.com/msazure/One/_build/results?buildId=61950645&view=results

• test is now using swifte2e/ciliume2e templates with new parameter testDropgz set to true.

• unit test stage has been reduced to only testing azure-ipam