Fix GitHub Actions build running out of disk space

This commit fixes the GitHub Actions build running out of disk space by removing the existing NDK image as we already install that manually.

.github/workflows/ci.yml

@@ -5,9 +5,6 @@ on: push
 jobs:
   build:
     runs-on: ubuntu-latest
-    container:
-      image: circleci/android:api-29-ndk
-      options: -u root
     env:
       JVM_OPTS: -Xmx6G
 
@@ -36,9 +33,6 @@ jobs:
     - name: Setup Environment for Gradle
       run: chmod +x gradlew
 
-    - name: Install CMake from Android SDK Manager
-      run: yes | sdkmanager --install "ndk;21.0.6113669" "cmake;3.10.2.4988404" | grep -v = || true
-
     - name: Android Lint
       run: ./gradlew --stacktrace lint