[FlINK-36392] Don't quote it?

Author: SamBarker

Dockerfile

@@ -25,7 +25,7 @@ WORKDIR /app
 
 COPY . .
 
-RUN --mount=type=bind,source="${MAVEN_HOME}",target=/root/.m2 \
+RUN --mount=type=bind,source=${MAVEN_HOME},target=/root/.m2 \
      mvn -ntp clean install \
     -pl flink-kubernetes-standalone,flink-kubernetes-operator-api,flink-kubernetes-operator,flink-autoscaler,flink-kubernetes-webhook -DskipTests=$SKIP_TESTS