CI: Refactor Android workflow, use pre-installed SDK and NDK

No need to waste time downloading all this when it's readily available :)
Also use the official action to setup Java 8.

Also build both architectures (armv7 and arm64v8) and generate the APK,
so we can upload it.

Remove now unused and outdated `misc/ci/android-tools-linux.sh`.

(cherry picked from commit 5f19e1d571)

.github/workflows/android_builds.yml

@@ -23,17 +23,10 @@ jobs:
           sudo cp -f misc/ci/sources.list /etc/apt/sources.list
           sudo apt-get update
 
-      # Install dependencies
-      - name: Install Java, Android SDK and NDK
-        run: |
-          sudo apt-get install openjdk-8-jdk
-          sudo update-java-alternatives -s java-1.8.0-openjdk-amd64
-          echo "JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64" >> $GITHUB_ENV
-          java -version
-          misc/ci/android-tools-linux.sh
-          echo "ANDROID_HOME=$(pwd)/godot-dev/build-tools/android-sdk" >> $GITHUB_ENV
-          echo "ANDROID_NDK_ROOT=$(pwd)/godot-dev/build-tools/android-ndk" >> $GITHUB_ENV
-          source ~/.bashrc
+      - name: Set up Java 8
+        uses: actions/setup-java@v1
+        with:
+          java-version: 8
 
       # Upload cache on completion and check it out now
       - name: Load .scons_cache directory
@@ -56,7 +49,6 @@ jobs:
           # Optional - x64 or x86 architecture, defaults to x64
           architecture: 'x64'
 
-      # You can test your matrix by printing the current Python version
       - name: Configuring Python packages
         run: |
           python -c "import sys; print(sys.version)"
@@ -67,8 +59,13 @@ jobs:
       - name: Compilation
         env:
           SCONS_CACHE: ${{github.workspace}}/.scons_cache/
+          ANDROID_NDK_ROOT: /usr/local/lib/android/sdk/ndk-bundle
         run: |
-          scons target=release tools=no
+          scons target=release tools=no android_arch=armv7
+          scons target=release tools=no android_arch=arm64v8
+          cd platform/android/java
+          ./gradlew generateGodotTemplates
+          cd ../../..
           ls -l bin/
 
       - uses: actions/upload-artifact@v2