fix(tier4_control_launch): add allow_substs="true" to control launcher parameter including

[paulsohn]

Description

As vehicle_cmd_gate.param.yaml uses substitution:

/**:
  ros__parameters:
    update_rate: 10.0
    system_emergency_heartbeat_timeout: 0.5
    use_emergency_handling: true
    check_external_emergency_heartbeat: $(var check_external_emergency_heartbeat)
    # (...)

we need allow_substs="true" to activate the substitutions inside the parameter file.
We already have many param files for control, so instead of attaching allow_substs="true" for every param file reference at once (unlike #1821 , where 2 out of 3 <param from /> required this) I want to add this attribute for only where it's needed for now, and apply to other files in a separate PR.

Related link: autowarefoundation/autoware_universe#6250
Perception is already using the same allow_substs="true" config.

How was this PR tested?

Not directly.

This issue was revealed when I was working on semantics improvement of my pre-build launcher resolver tool roscope ( paulsohn/roscope#46 ) and by the same tool I've confirmed this patch gives the correct parameters.

Notes for reviewers

None.

Effects on system behavior

None, or fix check_external_emergency_heartbeat substitution skipping.

[github-actions]

Thank you for contributing to the Autoware project!

🚧 If your pull request is in progress, switch it to draft mode.

Please ensure:

• You've checked our contribution guidelines.
• Your PR follows our pull request guidelines.
• All required CI checks pass before marking the PR ready for review.