chore: Delete useless workflow

.github/workflows/android_build.yml

@@ -1,25 +0,0 @@
-name: Android CI
-
-on:
-  push:
-    branches: [ $default-branch ]
-  pull_request:
-    branches: [ $default-branch ]
-
-jobs:
-  build:
-
-    runs-on: ubuntu-latest
-
-    steps:
-    - uses: actions/checkout@v2
-    - name: set up JDK 11
-      uses: actions/setup-java@v2
-      with:
-        java-version: '11'
-        distribution: 'adopt'
-
-    - name: Grant execute permission for gradlew
-      run: chmod +x gradlew
-    - name: Build with Gradle
-      run: ./gradlew build