[atlas] Deprecating the old measurement UI

Dear all,

In October last year, we introduced a new UI for browsing and scheduling
measurements. For details, see:
https://labs.ripe.net/Members/suzanne_taylor_muzzin/ripe-atlas-new-measurements-ui-and-tagging


Your feedback about this was predominantly positive, and we’d like to thank
everyone who helped this development with suggestions and bug reports.

As stated at the time, we plan to deprecate and eventually remove the old
interface (both the UI and the "API" it used). Our timeline is the following:

1. We'll make the new UI the default, and remove links to the old UI from
the RIPE Atlas main menu, around 21 January. The old pages will still be
accessible if one reaches them from somewhere else, such as a browser
bookmark or hard-coded scripts.

2. Around the beginning of March, we'll remove the old pages from the system
(/atlas/udm.html and related pages). This step will include the "deep links"
that some of our users directly access to schedule and manage measurements
from scripts (notably /atlas/*udm*.json).

We'd like to encourage all of our users to switch to the new UI and API in
the following weeks, if you haven't already done so.

As always, we're happy to answer any questions or hear any feedback you
might have.

Regards,
Robert Kisteleki, for the RIPE Atlas team