Remove hardcoded git repo checkout for the repo opensearch-build

[tianleh]

We have noticed a few places where the build repo link is hardcoded for checkout. E.g
https://github.com/opensearch-project/opensearch-build/blob/ff40ffba5e96836eaf8a3d70f0b4444bf6d2ef2b/vars/buildDockerImage.groovy

https://github.com/opensearch-project/opensearch-build/blob/9a82a23231cfa6f07bc4fa677b43795fbe8f49ff/vars/detectDockerAgent.groovy

Developers need to modify these values to their folked repo name and branch which is lowering the development efficient. These values shall read from the local workspace or as params.

[tianleh]

cc @peterzhuamazon

[abhinavGupta16]

[triage] We can take in the repository url and the branch as parameters and default to main if not provided for places where we checkout opensearch-build within libraries.

[peterzhuamazon]

Apparently jenkins would pull git repo when pulling the jenkinsfile, so we can delete these git url calls once we confirm not needing them anymore.

Thanks.

[peterzhuamazon]

This is nearly done except @zelinh whitesource scan, but that one is ok as it does not need to specify other versions.
@zelinh can decide whether want to change it or not.

Thanks.

[peterzhuamazon]

This is nearly done except @zelinh whitesource scan, but that one is ok as it does not need to specify other versions. @zelinh can decide whether want to change it or not.

Thanks.

I have sent an PR to update here:
#2038