SAT-1237 - remove netlifycms from _config.yml

SAT-1237 - Admin interface exposed

PR Checklist

[x] Test Cloud.gov Pages preview for your branch for functionality - make sure all links and buttons work, javascript works as intended, and updates display as expected
- Preview link: https://cg-a72b65a7-73f0-4859-a1d7-dc953cf6ade8.sites.pages.cloud.gov/preview/gsa/search-gov-website/dawnpm-remove-netlifycms/
[NA] Conduct a HemingwayApp review of the content for plain language. Request plain language review in #helpwanted if needed before merging this PR
[x] Conduct a Lighthouse Audit via Chrome Developer Tools. Identify any issues that must be addressed before merging, and fix
[x] Ensure no non-public information is published in the commit messages