fix(tier4_map_launch): add allow_substs="true" to map launcher parameter including

[paulsohn]

Description

As pointcloud_map_loader.param.yaml (substitutions for $(var pointcloud_map_loader_param_path)) itself uses substitutions:

/**:
  ros__parameters:
    enable_whole_load: true
    enable_downsampled_whole_load: false
    enable_partial_load: true
    enable_selected_load: false

    # only used when downsample_whole_load enabled
    leaf_size: 3.0 # downsample leaf size [m]
    pcd_paths_or_directory: [$(var pointcloud_map_path)] # Path to the pointcloud map file or directory
    pcd_metadata_path: $(var pointcloud_map_metadata_path) # Path to pointcloud metadata file

we need allow_substs="true" to activate the substitutions inside the parameter file.
Similar to lanelet2_map_loader.param.yaml.

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 the PCD map loading issue.

[github-actions]

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