Azure terraform backend updates

[dtzar]

A short explanation of the proposed change:

• Remove azure-blobstore resource
• centralize and parameterize pcfnorm/rootfs image
• use terraform to manage backend state
• remove - get: pivnet-opsmgr from unnecessary tasks

An explanation of the use cases your change solves:

• Have terraform properly manage the backend state.
• Specify an updated universal pcfnorm/rootfs image with updated tag

Expected result after the change:

• Users can now do local changes in conjunction with Concourse pipeline create-infrastructure task to deployed terraform resources since the backend state is now managed by terraform.
• Users have the ability to specify a newer tag for the pcfnorm/rootfs image in one place and use it universally across the pipeline.

Current result before the change: The current configuration "bootstraps" the terraform state by copying a blank terraform state file and then mounts the blob storage terraform state file local to the container and terraform has no idea it has a backend state, behaving like it does operations from local-only. This can cause various undesired behaviors and is not a supported scenario for using terraform backend state.

The latest tag for the pcfnorm/rootfs is extremely old and today a lot of manual work has to be done to update the image used for all the tasks since they image is specified in separate task files and has no tag reference or central parameter.

• Links to any other associated PRs or issues:

• [x] I have viewed signed and have submitted the Contributor License Agreement

• [x] I have made this pull request to the master branch

• [x] I have run all the unit tests

Note: A few of the unit tests are already broken on master.

[cf-gitbot]

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The labels on this github issue will be updated when the story is started.