update variable definitions

Signed-off-by: Steve Peters <scpeters@intrinsic.ai>

Author: scpeters

.github/workflows/ci_dependencies_from_source.yaml

@@ -3,11 +3,16 @@ name: Ubuntu CI
 on:
   workflow_dispatch:
     inputs:
-      vcs_repo_file_url:
-        description: URL to vcs repo file to import into colcon workspace
+      vcs-repo-file-is-relative:
+        description: If true the vcs-repo-file is a relative path in the github workspace; otherwise it is a URL.
+        type: bool
+        required: True
+        default: True
+      vcs-repo-file:
+        description: Relative path or URL to vcs repo file to import into colcon workspace
         required: true
         type: string
-        default: "${{ github.workspace }}/.github/ci/packages_up_to_sdformat.yaml"
+        default: ".github/ci/packages_up_to_sdformat.yaml"
 
 jobs:
   noble-ci:
@@ -23,7 +28,7 @@ jobs:
         with:
           package-name: sdformat
           target-ros2-distro: kilted
-          vcs-repo-file-url: "${{ inputs.vcs_repo_file_url }}"
+          vcs-repo-file-url: ${{ inputs.vcs-repo-file-is-relative && format('{0}/', github.workspace) }}${{ inputs.vcs-repo-file }}
           colcon-defaults: |
             {
               "build": {