ci: enable manual e2e runs on any git ref

Signed-off-by: Paul Meyer <49727155+katexochen@users.noreply.github.com>

.github/workflows/e2e-test-manual.yml

@@ -55,6 +55,11 @@ on:
         type: string
         default: "default"
         required: false
+      git-ref:
+        description: "Git ref to checkout."
+        type: string
+        default: "head"
+        required: false
 
 env:
   ARM_CLIENT_ID: ${{ secrets.AZURE_E2E_CLIENT_ID }}
@@ -84,10 +89,16 @@ jobs:
             exit 0
           fi
 
-      - name: Checkout
+      - name: Checkout head
+        if: inputs.git-ref == 'head'
         uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
         with:
           ref: ${{ !github.event.pull_request.head.repo.fork && github.head_ref || '' }}
+      - name: Checkout ref
+        if: inputs.git-ref != 'head'
+        uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
+        with:
+          ref: ${{ inputs.git-ref }}
 
       - name: Find latest image
         id: find-latest-image
@@ -104,10 +115,16 @@ jobs:
       contents: read
     needs: [find-latest-image]
     steps:
-      - name: Check out repository
+      - name: Checkout head
+        if: inputs.git-ref == 'head'
         uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
         with:
           ref: ${{ !github.event.pull_request.head.repo.fork && github.head_ref || '' }}
+      - name: Checkout ref
+        if: inputs.git-ref != 'head'
+        uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
+        with:
+          ref: ${{ inputs.git-ref }}
 
       - name: Setup Go environment
         uses: actions/setup-go@6edd4406fa81c3da01a34fa6f6343087c207a568 # v3.5.0