[SPARK-32772][SQL][FOLLOWUP] Remove legacy silent support mode for spark-sql CLI

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

Remove legacy silent support mode for spark-sql CLI.

### Why are the changes needed?

#29619 add new silent mode. We can remove legacy silent support mode.

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

No.

### How was this patch tested?

Manual test:
```
spark-sql> LM-SHC-16508156:spark yumwang$ bin/spark-sql -S
NOTE: SPARK_PREPEND_CLASSES is set, placing locally compiled Spark classes ahead of assembly.
20/09/03 09:06:12 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Using Spark's default log4j profile: org/apache/spark/log4j-defaults.properties
Setting default log level to "WARN".
To adjust logging level use sc.setLogLevel(newLevel). For SparkR, use setLogLevel(newLevel).
20/09/03 09:06:16 WARN HiveConf: HiveConf of name hive.stats.jdbc.timeout does not exist
20/09/03 09:06:16 WARN HiveConf: HiveConf of name hive.stats.retries.wait does not exist
20/09/03 09:06:19 WARN ObjectStore: Version information not found in metastore. hive.metastore.schema.verification is not enabled so recording the schema version 2.3.0
20/09/03 09:06:19 WARN ObjectStore: setMetaStoreSchemaVersion called but recording version is disabled: version = 2.3.0, comment = Set by MetaStore yumwang10.226.196.190
spark-sql> select * from test1;
1
spark-sql> select * from test1;
1

```

Closes #29631 from wangyum/SPARK-32772.

Authored-by: Yuming Wang <yumwang@ebay.com>
Signed-off-by: Yuming Wang <yumwang@ebay.com>

Author: wangyum

sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLCLIDriver.scala

@@ -35,7 +35,6 @@ import org.apache.hadoop.hive.ql.Driver
 import org.apache.hadoop.hive.ql.processors._
 import org.apache.hadoop.hive.ql.session.SessionState
 import org.apache.hadoop.security.{Credentials, UserGroupInformation}
-import org.apache.log4j.Level
 import org.apache.thrift.transport.TSocket
 import sun.misc.{Signal, SignalHandler}
 
@@ -320,9 +319,6 @@ private[hive] class SparkSQLCLIDriver extends CliDriver with Logging {
   // because the Hive unit tests do not go through the main() code path.
   if (!isRemoteMode) {
     SparkSQLEnv.init()
-    if (sessionState.getIsSilent) {
-      SparkSQLEnv.sparkContext.setLogLevel(Level.WARN.toString)
-    }
   } else {
     // Hive 1.2 + not supported in CLI
     throw new RuntimeException("Remote operations not supported")