Fixes for GitHub Actions Deployments

[sdonohoo]

• Fix "location undefined" failure for terraform Prod infra deployment. terraform_st_location was not defined in config-infra-prod.yml
• Edits to config-infra-prod.yml and config-infra-dev.yml to make available settings and example values consistent.
• Fix ref check for set-dev-branch and set-prod-branch in tf-gha-deploy-infra.yml. Check failed and all deployments were Dev.
• Fix incorrect low priority vm value for AmlCompute cluster. 'LowPriority' not valid. Should be 'low_priority'.
• Remove extra "with:" line from tf-gha-deploy-infra.yml
• Comment out "on:push" to disable autorun of terraform infra deployment on initial commit before necessary credentials are configured.
• Duplicate set-env-branch across other workflows to remove hardcoded prod branch config
• cluster_tier parameter missing from batch compute create
• deploy training pipeline fails because training dataset doesn't exist. Added register-dataset step and cleaned up unnecessary step dependencies. register-environment/register-dataset/create-compute now run in parallel