Fix configtest option in init scripts

No need to export all the JAVA* related environment variables
for configtest. It needs a minimal set of variables to execute
bin/logstash --config-test. This was indirectly causing issues
when used with JMX options in LS_JAVA_OPTS. JMX needs a remote port defined
and configtest was trying to connect to the port twice which caused
restart (#4319) to fail

Fixes #4319

Fixes #4759

pkg/logstash.sysv

@@ -142,7 +142,7 @@ configtest() {
   fi
 
   HOME=${LS_HOME}
-  export PATH HOME JAVA_OPTS LS_HEAP_SIZE LS_JAVA_OPTS LS_USE_GC_LOGGING
+  export PATH HOME
 
   test_args="--configtest -f ${LS_CONF_DIR} ${LS_OPTS}"
   $program ${test_args}