Misleading URI for labels in Merge Requests view

📝 This is very similar to #20031 (closed), but affects a different view.

Steps to reproduce

1. Select the menu in the top left → Merge Requests
2. Change Assignee to Any Assignee

Actual results

The URI in the address bar is the following:

https://gitlab.com/dashboard/merge_requests?scope=all&sort=id_desc&state=opened&utf8=%E2%9C%93&label-name=

Note the presence of the label-name query parameter.

Expected results

The query parameter for filtering by label name is label_name. The URI should either omit the label-name filter altogther, or, if intended for discovery purposes, use label_name instead.