chore: tup-463 remove temp. core-styles imports

[wesleyboar]

Overview

Remove temporary Core-Styles imports, because CMS's core-styles.portal.css has newer version.

• Some Core-Styles were loaded via CDN, cuz CMS did not have latest yet.
• Now CMS has much more recent Core-Styles, so use them. Do not duplicate.

Related

• TUP-463

Changes

• removed temporary Core-Styles imports

Testing

1. c-nav:
   1. Open MFA pairing or unpairing process.
   2. The header links at the top-right should match prod.
   3. There should be no duplicate CSS.
2. c-form:
   1. Open all forms.
   2. The form styles should match prod.
   3. There should be no duplicate CSS.
3. s-affixed-input-wrapper:
   1. Open MA pairing process.
   2. Click to generate QR code.
   3. The styles for alt. text code to copy should match prod.
   4. There should be no duplicate CSS.
4. Login Form
   1. Open login form.
   2. Styles should mostly* match prod.†
   3. Duplicate CSS is allowed.†

* The submit button may be taller. PR #376 fixes this.
† PR #376 will tackle Login Form, because it is less simple to clean up.

UI

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