refactor: change back to just using 1 environment for approval

to get a nicer looking environment name, e.g. use the workspace name,
we would have to do a 'composed' pipeline since the environment property
cannot be a variable - see https://stackoverflow.com/q/68545603

this doesn't seem worth it, so going back to just using a simple name

experiment-pipeline.yml

@@ -98,7 +98,7 @@ stages:
     jobs:
       - deployment: Apply
         condition: succeeded()
-        environment: dependencies.TerraformPlan.outputs['Plan.WORKSPACE']
+        environment: Approval
         strategy:
           runOnce:
             deploy: