phoebus.bat: Don't use server mode

[kasemir]

Mention -server 4918 in comment, but don't include it in the default parameters because it prevents opening multiple instances. In addition, that TCP port may be used by other tools, so leave addition of -server... settings to each site.

See also end user questions like https://epics.anl.gov/tech-talk/2023/msg00299.php

[kasemir]

@shroffk @georgweiss This is a change for those who simply use the 'phoebus.bat' without any local changes.
I assume, however, that most people would expect a new instance whenever invoking 'phoebus.bat'.
Including -server 4918 risks issues with something already using that port, including some hung instance of the launcher, so it's likely better to leave adding -server ... to whoever creates a launcher for local usage.