Do not output log on bash autocomplete generation as it requires
manual sanitizing. For instance, when running `openstack complete`,
it appends the following two lines:
~~~
complete -F _openstack openstack
2022-05-10 12:50:25.052 863 INFO osc_lib.shell [-] END return value: 0
~~~
and in the current .spec file, we manually remove the `complete -F`
line but we still get that LOG.info output in train at least. This
behavior was not seen on master/wallaby.
Change-Id: Id99791831ffc145b10a0ec8c211a99f8a714fa0a