Remove UTM parameter stripping

Created by: dadlerj

Requested by @lorihey @rebecca-rissinger

I've made the important edits to the relevant code here, but I am not the right person to get this merged...

Because Farhan is on vacation, and my dev environment is wildly outdated (I haven't worked in the sourcegraph/sourcegraph codebase since 2020), I would love support from someone on the frontend eng team to help ensure that these changes don't break anything!