fix GH Actions errors with CI

.github/workflows/integration_tests.yml

@@ -1,5 +1,6 @@
 name: Run Integration Tests
-on: {}
+on:
+  workflow_dispatch:
 
 jobs:
   run_integration_tests:

.github/workflows/jbpresubmit.yml

@@ -5,7 +5,8 @@
 
 # The aim of this workflow is to run checks and some tests before submitting the CL upstream.
 name: JB-COMPOSE-variant of AndroidX Presubmits
-on: {}
+on:
+  workflow_dispatch:
 
 jobs:
   setup:

.github/workflows/presubmit.yml

@@ -1,5 +1,6 @@
 name: AndroidX Presubmits
-on: {}
+on:
+  workflow_dispatch:
 
 env:
   # Allow precise monitoring of the save/restore of Gradle User Home by `gradle-build-action`

.github/workflows/prune_artifacts.yml

@@ -1,5 +1,6 @@
 name: "Prune old artifacts"
-on: {}
+on:
+  workflow_dispatch:
 
 jobs:
   delete-artifacts:

.github/workflows/register_workflow_start.yml

@@ -1,5 +1,6 @@
 name: Register Workflow Run with AndroidX
-on: {}
+on:
+  workflow_dispatch:
 
 jobs:
   ping_androidx_dev:

.github/workflows/scorecards.yml

@@ -1,5 +1,6 @@
 name: Scorecards supply-chain security
-on: {}
+on:
+  workflow_dispatch:
 
 # Declare default permissions as read only.
 permissions: read-all

.github/workflows/update_prebuilts.yml

@@ -2,7 +2,9 @@
 # To run it, navigate to https://github.com/androidx/androidx/actions/workflows/update_prebuilts.yml
 # and click "Run workflow"
 name: Update Prebuilts
-on: {}
+on:
+  workflow_dispatch:
+
 jobs:
   update-prebuilts:
     runs-on: ubuntu-latest