Kiali retention does not work as expected calendar times are greyed out in the dashboard graph

After setting prometheus retention over 1day in the SMCP, this updates the storageTsdbRetention setting in Kiali, but the times are greyed out in Kiali for all days in the calendar on the graph.

Steps:

1. Set the prometheus retention over 1 day
~~~
prometheus:
enabled: true
install:
retention: 14d
~~~

2. Check the custom calendar on the graph page the times for all days are grayed out.

Expected: The times should not be grayed out.