software/theia: set PS1

This runs in a go workspace, but we don't need to always have the
(gowork) marker.

software/theia/software.cfg

@@ -202,6 +202,8 @@ template =
   export PATH=${nodejs:location}/bin/:${python-language-server:location}/bin/:${bash:location}/bin/:${git:location}/bin/:$PATH
   . ${gowork:env.sh}
   export SHELL=bash
+  # reset PS1 from gowork
+  export PS1='$ '
   cd ${theia:location}
   exec ${yarn:location}/bin/yarn theia start $@