Update CTIS documentation to point to ICPSR

[capnrefsmmat]

Now that the CTIS data is archived with ICPSR, we can point there and deprecate pages describing access to microdata via CMU. ICPSR also archives the contingency tables, including a user guide, so we can remove the redundant contingency table documentation and point to ICPSR instead.

Prerequisites:

• Unless it is a documentation hotfix it should be merged against the dev branch
• Branch is up-to-date with the branch to be merged with, i.e. dev
• Build is successful
• Code is cleaned up and formatted

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[melange396]

Looks good to me! Do we need to do anything to remove data from https://www.cmu.edu/delphi-web/surveys/* (since we are removing all the references to it)?

[capnrefsmmat]

I don't think we need to delete the aggregate data yet -- I dunno if there are other links to it -- but we can do that as we also decommission the microdata SFTP access and move people over to ICPSR.