mgr/dashboard: handle infinite values for pools

mgr/dashboard: handle infinite values for pools

Fixes https://tracker.ceph.com/issues/64724

Issue:
======
Json parsing is failing because of Infinity values present in pools
meteadata. "read_balance": {"score_acting": Infinity, "score_stable":
Infinity,}
Due to this entire pool list is not rendered.

Fix:
====
Added a handler for checking "inf" values and replacing them with a
string "Infinity" so that json parsing does not fail on frontend.

Signed-off-by: Afreen <afreen23.git@gmail.com>