Allow deployment of feature branch images via the terraform pipeline

After feedback from some of the dev teams it is clear that we need to be able to deploy images from feature branches to the development workspace on an adhoc basis as and when required. The first step in enabling this is to configure the artifact registry template to run on non-default branches. Therefore, This MR adds a manual artifact registry push job for non-default branches while maintaining the automatic push job for pipelines running on the default branch.

The MR also includes a couple of tweaks to the terraform-pipeline which are semi-relevant but need doing, these are:

• Exclude some of the default tfsec checks that we don't adhere to.
• Tweak the development apply job to allow failure so that the whole pipeline shows as successful even if the manual dev apply job is not triggered.

Example pipeline with the artifact registry manual push job - https://gitlab.developers.cam.ac.uk/uis/devops/experiments/webapp-demo/webapp-test/-/jobs/1052483. Note that it contains a very obvious print of the container image url at the end of the job which will be useful for devs wishing to quickly grab the url to deploy to development for testing.

Part of #51 (closed)