* [forwardport] fix(webconnectivity): send specific user agent (#615)
This forward ports b8c530388e66b2cc86abad26d077202782e4a823 to `master`.
See https://github.com/ooni/probe/issues/1902
* fix(websteps): send the correct user agent
Also related to https://github.com/ooni/probe/issues/1902: let's just
ensure that also websteps behaves in the correct way.