src/pybind/mgr/pg_autoscaler/module.py: fix 'pg_autoscale_mode' output

src/pybind/mgr/pg_autoscaler/module.py: fix 'pg_autoscale_mode' output

Problem:
`ceph osd pool autoscale-status -f json`
and `ceph osd pool autoscale-status`
shows discrepeencies between each other
in the `pg_autoscale_mode` section,
when `no_autoscale` flag is set.

Solution:

set `pg_autoscale_mode` to `false` for
both `ceph osd pool autoscale-status` and
the json version of the command if `no_autoscale`
is set.

Fixes: https://tracker.ceph.com/issues/63860
Signed-off-by: Kamoltat <ksirivad@redhat.com>