Revert "Switch to GH actions."

This reverts commit 04ef589ad2.

.github/workflows/maven.yml

@@ -1,35 +0,0 @@
-# This workflow will build a Java project with Maven
-# For more information see: https://help.github.com/actions/language-and-framework-guides/building-and-testing-java-with-maven
-
-name: Build
-
-on:
-  push:
-    branches: [ 2.2.x ]
-  pull_request:
-    branches: [ 2.2.x ]
-
-jobs:
-  build:
-
-    runs-on: ubuntu-latest
-
-    strategy:
-      matrix:
-        java: ["8", "11", "16"]
-
-    steps:
-      - uses: actions/checkout@v2
-      - name: Set up JDK 1.8
-        uses: actions/setup-java@v1
-        with:
-          java-version: 1.8
-      - name: Cache local Maven repository
-        uses: actions/cache@v2
-        with:
-          path: ~/.m2/repository
-          key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
-          restore-keys: |
-            ${{ runner.os }}-maven-
-      - name: Build with Maven
-        run: ./mvnw clean install -B -U