Move mention of Contact from core help to contact module

Problem/Motivation

Contact is being deprecated, see the parent issue for details. This issue is for removing Contact from the standard profile.

For an example see how this was done for the RDF module in #3243121: Remove RDF module from the Standard profile → .

Steps to reproduce

Proposed resolution

Remove Contact module from the core help module.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet

TBA