Deprecate /deliveryservice_user/:dsId/:userId

[mhoppa]

What does this PR (Pull Request) do?

• This PR fixes Rewrite /deliveryservice_user/{{DSID}}/{{userID}} to Go #3837

Which Traffic Control components are affected by this PR?

• Documentation
• Traffic Ops

What is the best way to verify this PR?

Make request to /deliveryservice_user/:dsId/:userId and ensure deprecation notice is returned and then build docs and make sure they render correctly with deprecation notice on it.

If this is a bug fix, what versions of Traffic Control are affected?

The following criteria are ALL met by this PR

• This PR includes tests OR I have explained why tests are unnecessary
• This PR includes documentation OR I have explained why documentation is unnecessary
• This PR includes an update to CHANGELOG.md OR such an update is not necessary
• This PR includes any and all required license headers
• This PR ensures that database migration sequence is correct OR this PR does not include a database migration
• This PR DOES NOT FIX A SERIOUS SECURITY VULNERABILITY (see the Apache Software Foundation's security guidelines for details)

Additional Information

[ocket8888]

Observed deprecation notices in responses to manual requests, docs look good and compile without errors/warnings.