ui: custom time series charts don't refresh automatically when updating the y-axis units

[xinhaoz]

Describe the problem

Please describe the issue you observed, and any steps we can take to reproduce it: On db console custom time series page, select a metric and change the y-axis unit:

The graph does not update with the new unit, unless a refresh is triggered elsewhere.

Expected behavior The graph should update immediately with the new units.

Jira issue: CRDB-39004

Epic CRDB-32130

[blathers-crl[bot]]

Hi @xinhaoz, please add branch-* labels to identify which branch(es) this C-bug affects.

_{:owl: Hoot! I am a Blathers, a bot for CockroachDB. My owner is dev-inf.}