Remove SonarCloud from workflow

It is useless in most of our workflows, since our PRs mostly come from
external forks, which cannot access the secret SONAR_TOKEN.

Running SonarCloud on automatic instead.

.github/workflows/build-and-test.yml

@@ -116,16 +116,4 @@ jobs:
             echo
           done
 
-  sonarcloud:
-      name: SonarCloud
-      runs-on: ubuntu-latest
-      steps:
-        - uses: actions/checkout@v2
-          with:
-            fetch-depth: 0  # Shallow clones should be disabled for a better relevancy of analysis
-        - name: SonarCloud Scan
-          uses: SonarSource/sonarcloud-github-action@master
-          env:
-            GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}  # Needed to get PR information, if any
-            SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}