qitoolchain remove: fix #6610
qitoolchain remove: fix #6610

* Now emits a warning when toolchain does not exist
* Use qibuild.ui

Change-Id: I4c1d6fb065df59e4a24ea5104766c6307e313e8a
Reviewed-on: http://gerrit.aldebaran.lan:8080/3547
Reviewed-by: dmerejkowsky <1e4b13000fa8777df4cefd2fd8215187e3deb062@aldebaran-robotics.com>
Tested-by: dmerejkowsky <1e4b13000fa8777df4cefd2fd8215187e3deb062@aldebaran-robotics.com>

dmerejkowsky/qibuild,dmerejkowsky/qibuild,dmerejkowsky/qibuild,aldebaran/qibuild,dmerejkowsky/qibuild,aldebaran/qibuild,aldebaran/qibuild,dmerejkowsky/qibuild,aldebaran/qibuild