Remove completer

I can explore this topic later if we want it. We could use a Python
library like argcomplete to automatically generate this if we want it,
or I can write a simple bash completion script.

Author: pedro-avalos

cli/snapcraft.yaml

@@ -22,7 +22,6 @@ architectures:
 apps:
   testflinger-cli:
     command: testflinger-cli
-    completer: testflinger-completion
     environment:
       LC_ALL: C.UTF-8
       LANG: C.UTF-8