ci: Run normal CI workflow on pushes to main (#618)

This should ensure that everything that is built as part of regular CI
can be saved to the build cache after the PR is merged.

.github/workflows/ci.yml

@@ -4,6 +4,8 @@ on:
   push:
     tags:
       - '*'
+    branches:
+      - main
   pull_request:
   workflow_dispatch:
 

.github/workflows/populate-gradle-build-cache.yml

@@ -1,28 +0,0 @@
-# Build the app on each push to `main`, populating the build cache to speed
-# up CI on PRs.
-
-name: Populate build cache
-
-on:
-  push:
-    branches:
-      - main
-
-jobs:
-  build:
-    strategy:
-      matrix:
-        color: ["orange"]
-        store: ["fdroid", "github", "google"]
-    name: Build
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
-
-      - uses: ./.github/actions/setup-build-env
-        with:
-          gradle-cache-encryption-key: ${{ secrets.GRADLE_ENCRYPTION_KEY }}
-
-      - name: Build ${{ matrix.color }}${{ matrix.store }}Debug
-        run: ./gradlew build${{ matrix.color }}${{ matrix.store }}Debug