Make TerminalIPythonApp message configurable while loading bsui 

Requested by @andrewmkiss in https://github.com/NSLS-II-SRX/profile_collection/issues/18#issuecomment-761211890:

> While loading bsui, we see a message [TerminalIPythonApp] Running file in user namespace...[filepath + name]. And then I have my own (much shorter), Loading file {filename}.... Can we remove this TerminalIPython message?

