change(ci): Add patch jobs for lightwalletd build and getblocktemplat…

…e-rpcs tests (ZcashFoundation#5474)

* Add test-all-getblocktemplate-rpcs CI patch job

* Cancel concurrent in-progress zcash-lightwalletd jobs

* Add a patch job for zcash-lightwalletd / Build images

.github/workflows/continous-integration-docker.patch.yml

@@ -42,6 +42,12 @@ jobs:
     steps:
       - run: 'echo "No build required"'
 
+  test-all-getblocktemplate-rpcs:
+    name: Test all with getblocktemplate-rpcs feature
+    runs-on: ubuntu-latest
+    steps:
+      - run: 'echo "No build required"'
+
   test-fake-activation-heights:
     name: Test with fake activation heights
     runs-on: ubuntu-latest

.github/workflows/zcash-lightwalletd.patch.yml

@@ -0,0 +1,22 @@
+name: zcash-lightwalletd
+
+# When the real job doesn't run because the files aren't changed,
+# run a fake CI job to satisfy the branch protection rules.
+on:
+  pull_request:
+    branches:
+      - main
+    paths-ignore:
+      - 'zebra-rpc/**'
+      - 'zebrad/tests/acceptance.rs'
+      - 'zebrad/src/config.rs'
+      - 'zebrad/src/commands/start.rs'
+      - 'docker/zcash-lightwalletd/Dockerfile'
+      - '.github/workflows/zcash-lightwalletd.yml'
+
+jobs:
+  build:
+    name: Build images
+    runs-on: ubuntu-latest
+    steps:
+      - run: 'echo "No build required"'

.github/workflows/zcash-lightwalletd.yml

@@ -1,5 +1,14 @@
 name: zcash-lightwalletd
 
+# Ensures that only one workflow task will run at a time. Previous builds, if
+# already in process, will get cancelled. Only the latest commit will be allowed
+# to run, cancelling any workflows in between
+#
+# Cancelling old jobs is the most efficient approach, because the workflow is quick.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
 on:
   workflow_dispatch: