rubiconBidAdapter tests: please migrate querystring to URLSearchParams

[dgirardi]

The rubiconBidAdapter tests rely on querystring:

Prebid.js/test/spec/modules/rubiconBidAdapter_spec.js

Line 11 in babd603

import {parse as parseQuery} from 'querystring';

With 9, this had to be explicitly included as a dependency - probably because it was included indirectly through now-removed other dependencies (https://app.circleci.com/pipelines/github/prebid/Prebid.js/21362/workflows/c1660a29-4ce6-4a7b-8dca-b790cf024784/jobs/38114)

Nowadays parsing query strings can be done without relying on an external library - the tests should be updated to use URLSearchParams.

[dgirardi]

@harpere @robertrmartinez tagging you as I'm not sure you've acknowledged this yet

[robertrmartinez]

Acking now @dgirardi !

Will get it done.