[SPARK-33408][SPARK-32354][K8S][R] Use R 3.6.3 in K8s R image and re-…

…enable RTestsSuite

### What changes were proposed in this pull request?

This PR aims to use R 3.6.3 in K8s R image and re-enable `RTestsSuite`.

### Why are the changes needed?

Jenkins Server is using `R 3.6.3`.
```
+ SPARK_HOME=/home/jenkins/workspace/SparkPullRequestBuilder-K8s
+ /usr/bin/R CMD check --as-cran --no-tests SparkR_3.1.0.tar.gz
* using log directory ‘/home/jenkins/workspace/SparkPullRequestBuilder-K8s/R/SparkR.Rcheck’
* using R version 3.6.3 (2020-02-29)
```

OpenJDK docker image is using `R 3.5.2 (2018-12-20)` which is old and currently `spark-3.0.1` fails to run SparkR.
```
$ cd spark-3.0.1-bin-hadoop3.2

$ bin/docker-image-tool.sh -R kubernetes/dockerfiles/spark/bindings/R/Dockerfile -n build
...
	 exit code: 1
	 termination reason: Error
...

$ bin/spark-submit --master k8s://https://192.168.64.49:8443 --deploy-mode cluster --conf spark.kubernetes.container.image=spark-r:latest local:///opt/spark/examples/src/main/r/dataframe.R

$ k logs dataframe-r-b1c14b75b0c09eeb-driver
...
+ exec /usr/bin/tini -s -- /opt/spark/bin/spark-submit --conf spark.driver.bindAddress=172.17.0.4 --deploy-mode client --properties-file /opt/spark/conf/spark.properties --class org.apache.spark.deploy.RRunner local:///opt/spark/examples/src/main/r/dataframe.R
20/11/10 06:03:58 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
log4j:WARN No appenders could be found for logger (io.netty.util.internal.logging.InternalLoggerFactory).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
Error: package or namespace load failed for ‘SparkR’ in rbind(info, getNamespaceInfo(env, "S3methods")):
 number of columns of matrices must match (see arg 2)
In addition: Warning message:
package ‘SparkR’ was built under R version 4.0.2
Execution halted
```

In addition, this PR aims to recover the test coverage.

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

Pass K8S IT Jenkins job.

Closes #30130 from dongjoon-hyun/SPARK-32354.

Authored-by: Dongjoon Hyun <dongjoon@apache.org>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>

resource-managers/kubernetes/docker/src/main/dockerfiles/spark/bindings/R/Dockerfile

@@ -25,7 +25,14 @@ USER 0
 
 RUN mkdir ${SPARK_HOME}/R
 
-RUN apt-get update && apt install -y r-base r-base-dev && rm -rf /var/cache/apt/*
+# Install R 3.6.3 (http://cloud.r-project.org/bin/linux/debian/)
+RUN \
+  echo "deb http://cloud.r-project.org/bin/linux/debian buster-cran35/" >> /etc/apt/sources.list && \
+  apt install -y gnupg && \
+  apt-key adv --keyserver keys.gnupg.net --recv-key 'E19F5F87128899B192B1A2C2AD5F960A256A04AF' && \
+  apt-get update && \
+  apt install -y -t buster-cran35 r-base r-base-dev && \
+  rm -rf /var/cache/apt/*
 
 COPY R ${SPARK_HOME}/R
 ENV R_HOME /usr/lib/R

resource-managers/kubernetes/integration-tests/src/test/scala/org/apache/spark/deploy/k8s/integrationtest/KubernetesSuite.scala

@@ -43,8 +43,7 @@ import org.apache.spark.internal.config._
 class KubernetesSuite extends SparkFunSuite
   with BeforeAndAfterAll with BeforeAndAfter with BasicTestsSuite with SecretsTestsSuite
   with PythonTestsSuite with ClientModeTestsSuite with PodTemplateSuite with PVTestsSuite
-  // TODO(SPARK-32354): Fix and re-enable the R tests.
-  with DepsTestsSuite with DecommissionSuite /* with RTestsSuite */ with Logging with Eventually
+  with DepsTestsSuite with DecommissionSuite with RTestsSuite with Logging with Eventually
   with Matchers {