Install e2e test chart without make/deploy

[avorima]

Description

I added the deploy/image-ref target to be fully compatible with make deploy, otherwise the image would not match in most cases.

DAQ-14405

How can this be tested?

Run any e2e test and see if the chart is installed correctly.

Test run: https://github.com/Dynatrace/dynatrace-operator/actions/runs/19765900821/job/56638503176

[andriisoldatenko]

Did a quick test on GKE, and it works!

[avorima]

Verify the format fix:

.github/workflows/test.yml

name: Test format
on:
  pull_request:
  workflow_dispatch:
    inputs:
      target:
        description: Target
        required: true
        default: 'main'
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - run: echo $MYVAR
        env:
          MYVAR: ${{ format('{0}-fips', github.event.inputs.target || 'main') }}

act pull_request -W .github/workflows/test.yml
act workflow_dispatch --input target=foo -W .github/workflows/test.yml