[GitHub][web-base] Remove the reset password feature via the primary email address

[huabin]

Detailed description according to the following.

The service or application that you want to submit an issue to
GitHub.com

What feature and where in the system

• Go to https://github.com/settings/emails

Current Status
Password can be reset via primary email address.

The way you want it to be
Remove the reset password feature via the primary email address

Reason
Primary email address is the default used for GitHub notifications, i.e., replies to issues, pull requests, etc. And it may be used as the 'author' or 'committer' address for web-based Git operations, e.g., edits and merges.

It is public and will be known by others, it should not be used for password reset and security related operations.

Additional context
There are two issues 1, 2, they can leak the primary email address.