mgr/dashboard: Fix Latency chart data units in rgw overview page

mgr/dashboard: Fix Latency chart data units in rgw overview page

Issue: The Latency chart in the rgw overview page shows incorrect data
unit as the unit that we are passing as an input to the dashboard-area
chart component is `ms` whereas the data that we get from the metrics is
in seconds. Due to this if we pass a value like 0.725s to
the dashboard chart component it will show the value in the chart as
0.725ms whereas it should be 725ms.

Fix: Pass the value in ms as expected to the dashboard area chart
component

Fixes: https://tracker.ceph.com/issues/69144
Signed-off-by: Aashish Sharma <aasharma@redhat.com>