Code review comment for ~peter-sabaini/charm-graylog:lp1758175

Graylog service not starting snap version is 3/stable with tls enabled:

2021-01-22T21:13:21Z systemd[1]: Started Service for snap application graylog.graylog.
2021-01-22T21:13:36Z systemd[1]: snap.graylog.graylog.service: Main process exited, code=exited, status=255/n/a
2021-01-22T21:13:36Z systemd[1]: snap.graylog.graylog.service: Failed with result 'exit-code'.

graylog traceback has this as the cause:

        Caused by: org.glassfish.grizzly.ssl.SSLContextConfigurator$GenericStoreException: java.io.FileNotFoundException: /var/snap/graylog/common/cacerts (No such file or directory)

Snap is running graylog with the following cli args: (most specifically: -Djavax.net.ssl.trustStore=/var/snap/graylog/common/cacerts)

root 7680 1 0 21:24 ? 00:00:03 /snap/graylog/17/usr/lib/jvm/java-8-openjdk-amd64/bin/java -Djavax.net.ssl.trustStore=/var/snap/graylog/common/cacerts -jar -Dlog4j.configurationFile=file:///snap/graylog/17/etc/graylog/server/log4j2.xml -Djava.library.path=/snap/graylog/17/usr/share/graylog-server/lib/sigar -Dgraylog2.installation_source=snap /snap/graylog/17/usr/share/graylog-server/graylog.jar server -f /var/snap/graylog/common/server.conf -np