[SPARK-53125][TEST] RemoteSparkSession prints whole spark-submit command

[pan3793]

What changes were proposed in this pull request?

Make RemoteSparkSession print the whole spark-submit command in debug mode, which helps the developers to understand the SPARK_HOME, classpath, log output, etc. of the testing connect server process.

Why are the changes needed?

Improve the debug message.

Does this PR introduce any user-facing change?

No.

How was this patch tested?

export SPARK_DEBUG_SC_JVM_CLIENT=true

sbt:spark-connect-client-jvm> testOnly *ClientE2ETestSuite -- -z "throw SparkException with large cause exception"
[info] ClientE2ETestSuite:
Starting the Spark Connect Server...
Using jar: /Users/chengpan/Projects/apache-spark/sql/connect/server/target/scala-2.13/spark-connect-assembly-4.1.0-SNAPSHOT.jar
Using jar: /Users/chengpan/Projects/apache-spark/sql/catalyst/target/scala-2.13/spark-catalyst_2.13-4.1.0-SNAPSHOT-tests.jar
/Users/chengpan/Projects/apache-spark/bin/spark-submit \
    --driver-class-path /Users/chengpan/Projects/apache-spark/sql/connect/server/target/scala-2.13/spark-connect-assembly-4.1.0-SNAPSHOT.jar \
    --class org.apache.spark.sql.connect.SimpleSparkConnectService \
    --jars /Users/chengpan/Projects/apache-spark/sql/catalyst/target/scala-2.13/spark-catalyst_2.13-4.1.0-SNAPSHOT-tests.jar \
    --conf spark.connect.grpc.binding.port=15707 \
    --conf spark.sql.catalog.testcat=org.apache.spark.sql.connector.catalog.InMemoryTableCatalog \
    --conf spark.sql.catalogImplementation=hive \
    --conf spark.connect.execute.reattachable.senderMaxStreamDuration=1s \
    --conf spark.connect.execute.reattachable.senderMaxStreamSize=123 \
    --conf spark.connect.grpc.arrow.maxBatchSize=10485760 \
    --conf spark.ui.enabled=false \
    --conf spark.driver.extraJavaOptions=-Dlog4j.configurationFile=/Users/chengpan/Projects/apache-spark/sql/connect/client/jvm/src/test/resources/log4j2.properties /Users/chengpan/Projects/apache-spark/sql/connect/server/target/scala-2.13/spark-connect-assembly-4.1.0-SNAPSHOT.jar
...

Was this patch authored or co-authored using generative AI tooling?

No.

[pan3793]

cc @HyukjinKwon