ci: run integration tests additionally on v7 branch (#316)

Integration tests were only running on the `v8` branch since
(apparently) cron schedule only works for the `default` branch.

This commit explicitly uses a matrix build to trigger v7/v8 integration
tests: `{v7, v8} x {production, staging}`.

I've also added a manual job to make it easy to target a particular
branch+environment.

.github/workflows/daily-integration-tests.yml

@@ -1,13 +1,9 @@
-name: 'Integration Tests'
+name: 'Daily Integration Tests'
 on:
   workflow_dispatch:
     inputs:
       go-version:
-        description: "Go version to use for building Relay."
-        required: false
-        type: string
-      branch:
-        description: "Branch to test."
+        description: "Go version to use for building Relay (leave empty for latest defined in repo.)"
         required: false
         type: string
 
@@ -25,9 +21,10 @@ jobs:
       fail-fast: false
       matrix:
         environment: ['staging', 'production']
+        branch: ['v7', 'v8']
 
     uses: ./.github/workflows/integration-test.yml
     with:
       environment: ${{ matrix.environment }}
       go-version: ${{ inputs.go-version != '' && inputs.go-version || needs.go-versions.outputs.latest }}
-      branch: ${{ inputs.branch }}
+      branch: ${{ matrix.branch }}

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

@@ -0,0 +1,26 @@
+name: 'Manual Integration Tests'
+on:
+  workflow_dispatch:
+    inputs:
+      go-version:
+        description: "Go version to use for building Relay (leave empty for latest defined in repo.)"
+        required: false
+        type: string
+      environment:
+        description: "The environment to test against."
+        type: choice
+        options:
+          - 'staging'
+          - 'production'
+
+jobs:
+  go-versions:
+    uses: ./.github/workflows/go-versions.yml
+
+  integration-test:
+    needs: go-versions
+    uses: ./.github/workflows/integration-test.yml
+    with:
+      environment: ${{ inputs.environment }}
+      go-version: ${{ inputs.go-version != '' && inputs.go-version || needs.go-versions.outputs.latest }}
+      branch: ${{ github.ref }}