CI: assume NDK + Java in official Ubuntu images

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ env:
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
       matrix:
@@ -40,15 +40,6 @@ jobs:
         # currently requires this crate to be buildable with 1.64
         run: cargo install cargo-ndk --version "^2"
 
-      - name: Setup Java
-        uses: actions/setup-java@v3
-        with:
-          distribution: 'temurin'
-          java-version: '17'
-
-      - name: Setup Android SDK
-        uses: android-actions/setup-android@v2
-
       - name: Build game-activity
         working-directory: android-activity
         run: >