[Enhancement] Change xml in start_fe to 8G (#23604)

If there are some Illegal characters in the fe.conf, the JAVA_OPTS will
be read in the start_fe.sh, but the Xmx in start_fe.sh is 1G, which will
cause OOM.
Set Xmx in start_fe.sh to 8G.

Signed-off-by: gengjun-git <gengjun@starrocks.com>

bin/start_fe.sh

@@ -60,7 +60,7 @@ source $STARROCKS_HOME/bin/common.sh
 # JAVA_OPTS
 # LOG_DIR
 # PID_DIR
-export JAVA_OPTS="-Xmx1024m"
+export JAVA_OPTS="-Xmx8g"
 export LOG_DIR="$STARROCKS_HOME/log"
 export PID_DIR=`cd "$curdir"; pwd`