Switching between labeled metrics doesn't reset `aggKey` and 'aggType' parameters

[edugfilho]

This causes the new metric to never load.
Steps to reproduce:
Go to https://glam.telemetry.mozilla.org/fog/probe/network_system_channel_addonversion_status/explore?aggKey=cancel&aggType=avg&ping_type=*

Use the search bar to search for urlbar_searchmode_other and pick the GLEAN one (Labeled Counter)

Notice the url parameters change with the metric name but keep aggKey and aggType to old values
As a consequence the data doesn't load and the spinning bar keeps going on...