Launcher should correctly reload JAVA_OPTS when modified by a marketplace package

When a package is installed through the admin center and modifies JAVA_OPTS, that change is not taken into account on the first restart.

Steps to reproduce with the kerberos-authentication package:

1) Configure kerberos (copy /opt/build/keystores/keytabs/krb5.conf to /etc/krb5.conf)

2) On a clean CAP 5.9.6-SNAPSHOT distribution,add the following parameters to nuxeo.conf:
kerberos.principal=HTTP/jenkins@AD.IN.NUXEO.COM
kerberos.keytab=/opt/build/keystores/keytabs/jenkins.keytab

3) Start nuxeo, register the instance and install the kerberos-authentication 1.3.0-SNAPSHOT package

4) Restart nuxeo

The server will start without "-Djava.security.auth.login.config=nxserver/config/java.login.config"

If you restart it again, that option will be added.