Output to `juju exec` is too verbose

[Peter Matulis]

The `exec` command in Juju v.3 is too verbose. Often a user is just querying a unit for information and I don't see why this output needs to be exposed to the user:

$ juju exec --unit keystone/leader 'leader-get admin_passwd'
Running operation 17 with 1 task
  - task 18 on unit-keystone-0

Waiting for task 18...
eozoh3saiFo6Aesh

Can we either:

a) suppress this output altogether
b) include a quiet option to suppress it
c) include a verbose option to see it

[Ian Booth (wallyworld)]

For exec, probably the default behavior should be "quiet", so it seems like a --verbose flag is what's needed.

[Jordan Barrett (barrettj12)]

`juju exec` already has --quiet and --verbose flags - in fact, I think every command does. In this case, the --verbose flag has no effect, whereas the --quiet flag suppresses the additional output as @petermatulis asked:
```
$ juju exec --machine 0 'echo hi'
Running operation 3 with 1 task
  - task 4 on machine-0

Waiting for task 4...
hi

$ juju exec --machine 0 'echo hi' --quiet
hi

$ juju exec --machine 0 'echo hi' --verbose
Running operation 7 with 1 task
  - task 8 on machine-0

Waiting for task 8...
hi

$
```

So, I think the only question is whether we want to make --quiet the default behaviour (I think we probably should).

@wallyworld surely we can target this to 2.9?

[Jordan Barrett (barrettj12)]

https://github.com/juju/juju/pull/14099