[hotfix] Make test_sql_client independent of unzip

Some platforms might not have installed the unzip command. Therefore it is
better to use the jar command to extract jar files.

flink-end-to-end-tests/test-scripts/test_sql_client.sh

@@ -36,7 +36,7 @@ mkdir -p $EXTRACTED_JAR
 
 for SQL_JAR in $SQL_JARS_DIR/*.jar; do
  echo "Checking SQL JAR: $SQL_JAR"
- unzip $SQL_JAR -d $EXTRACTED_JAR > /dev/null
+ (cd $EXTRACTED_JAR && jar xf $SQL_JAR)
 
  # check for proper shading
  for EXTRACTED_FILE in $(find $EXTRACTED_JAR -type f); do
@@ -60,6 +60,8 @@ for SQL_JAR in $SQL_JARS_DIR/*.jar; do
  rm -r $EXTRACTED_JAR/*
 done
 
+rm -r $EXTRACTED_JAR
+
 ################################################################################
 # Prepare connectors
 ################################################################################