Update step name, remove Jetpack install

.github/workflows/ci.yml

@@ -43,7 +43,7 @@ jobs:
         composer install --prefer-dist --no-suggest --no-progress --no-ansi --no-interaction
         echo "${PWD}/mu-plugins/vendor/bin" >> $GITHUB_PATH
 
-    - name: Run PHPCS on all Core files
+    - name: Run PHPCS on changed files
       run: |
         touch $GITHUB_WORKSPACE/tmp.php
         export CHANGED_FILES=$(git diff --name-only --diff-filter=AM remotes/origin/${{ github.base_ref }} | tr '\n' ' ')
@@ -90,9 +90,5 @@ jobs:
       run: |
         bash bin/install-wp-tests.sh wporg_5ftf_test root root 127.0.0.1 trunk
 
-    - name: Install required plugins
-      run: |
-        svn export https://plugins.svn.wordpress.org/jetpack/trunk public_html/wp-content/plugins/jetpack
-
     - name: Running unit tests
       run: composer run-script test -- -c phpunit.xml.dist