feat(pz): Add option to configure server memory usage (#4204)

lgsm/config-default/config-lgsm/pzserver/_default.cfg

@@ -10,10 +10,11 @@
 
 ## Predefined Parameters | https://docs.linuxgsm.com/configuration/start-parameters
 ip="0.0.0.0"
+javaram="8192" # -Xmx$8192M
 adminpassword="CHANGE_ME"
 
 ## Server Parameters | https://docs.linuxgsm.com/configuration/start-parameters#additional-parameters
-startparameters="--ip ${ip} -adminpassword \"${adminpassword}\" -servername ${selfname}"
+startparameters="--ip ${ip} -adminpassword \"${adminpassword}\" -servername ${selfname} -Xmx${javaram}M"
 
 #### LinuxGSM Settings ####