[testing workflows] Use choices for on-demand test run input (#50170)

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ on:
         type: string
 
 concurrency:
-  group: '${{ github.workflow }}-${{ github.ref }}'
+  group: '${{ github.workflow }}-${{ github.ref }}-${{ inputs.trigger }}'
   cancel-in-progress: true
 
 env:

.github/workflows/tests-on-demand.yml

@@ -4,14 +4,35 @@ on:
   workflow_dispatch:
     inputs:
       trigger:
-        description: 'Event name. It will be used to filter the jobs to run in ci.yml. It can be anything, as long as the job you want to run has this event configured in the `events` list. Example: daily-checks, pull_request, on-demand, etc.'
+        type: choice
+        description: 'Event name: it will be used to filter the jobs to run in ci.yml.'
         required: true
-        default: ''
+        options:
+          - push
+          - daily-checks
+          - pre-release
+          - on-demand
+          - custom
+        default: on-demand
+      custom-trigger:
+        type: string
+        description: 'Custom event name: In case the `Event name` choice is `custom`, this field is required.'
+        required: false
 
 jobs:
+  validate-input:
+    runs-on: ubuntu-latest
+    steps:
+      - name: 'Validate input'
+        run: |
+          if [ "${{ inputs.trigger }}" == "custom" ] && [ -z "${{ inputs.custom-trigger }}" ]; then
+            echo "Custom event name is required when event name choice `custom`."
+            exit 1
+          fi
+
   run-tests:
     name: 'Run tests'
     uses: ./.github/workflows/ci.yml
     with:
-      trigger: ${{ inputs.trigger }}
+      trigger: ${{ inputs.trigger == 'custom' && inputs.custom-trigger || inputs.trigger }}
     secrets: inherit