Continuous build

Don't close connection after each pass

Previously, the sim would close the connection and then start a new run upon re-connecting.
That wasn't compatible with libertem-live-server prototypes and didn't seem to correspond to the behavior
of the real detector software.

With this change, the sim will keep starting new acquisitions on the same connection
without closing it. This seems to work better.

Discusson with @sk1p: We should see if and when we want to simulate
the detector closing a connection. Effects of this change in the wild to be monitored!

Co-authored-by: Alexander Clausen <a.clausen@fz-juelich.de>