End to End Tests Plan Starter Modules

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Infrastructure as Code Type? (Required)

both

### Starter Module? (Required)

other

### Use Case (Required)

When we run end to end tests it would be great to get validation that at least the plan works for each starter module. The full apply is too lengthy and costly at this time.

### Proposed Solution (Required)

- Add a new attribute to the matrix for a `planOnly` run.
- Add matrix items for GitHub and Azure devops in addition to existing local.
- Update the ADO and GitHub scripts to support a plan only option.
- Add the relevant code to trigger the plan only run if that is set in the matrix.

Stretch goal.

- Run plan only for the local script too.

### Important Factoids (Optional)

_No response_

### References (Optional)

_No response_

Start by locating the end-to-end test matrix and the existing local, GitHub, and Azure DevOps scripts. Trace how matrix entries trigger runs, then add and verify the plan-only path for GitHub and Azure DevOps, with the local script as a stretch goal. Done means each starter module can be validated by a plan without a full apply.

Written by the indexing model from the issue text.