pybind/mgr/pg_autoscaler: Reorderd if statement for the func: _maybe_adjust

pybind/mgr/pg_autoscaler: Reorderd if statement for the func: _maybe_adjust

Problem:

In the func `_maybe_adjust` we have this condition
where `if not p['would_adjust']: continue` which
would get triggered before `if p['pg_autoscale_mode'] == 'warn':`
if we don't have `pg_autoscale_mode` as `on`. This causes:
the autoscaler to not throw any warnings.

Solution:
Move `if p['pg_autoscale_mode'] == 'warn':` to be
higher than `if not p['would_adjust']: continue`.

Fixes: https://tracker.ceph.com/issues/58894
Signed-off-by: Kamoltat <ksirivad@redhat.com>
(cherry picked from commit c43fe7f07631bd0d795b711a100b9220b996ace0)