Update "New Admin Email Address" Email Wording

[TwisterMc]

The wording of the email that a user gets when you change the administration email address on a site is confusing.

Current:

Howdy [name],

You recently requested to have the administration email address on your site changed.

If this is correct, please click on the following link to change it:
​https://example.com/wp-admin/options.php?adminhash=fcedb1537af41f16914d835e5d16d089

You can safely ignore and delete this email if you do not want to take this action.

This email has been sent to [your-email]

Regards,
All at [site-name]
[site-url]

Proposed Update:

Howdy [name],

The current administrator of [site-name] has updated the administration email address to your email address.

If you approve this change, please click on the following link to confirm the change:
​https://example.com/wp-admin/options.php?adminhash=fcedb1537af41f16914d835e5d16d089

If you do not approve, you can safely ignore and delete this email.

This email has been sent to [email-address]

Regards,
All at [site-name]
[site-url]

Reasoning

1. The email starts out with "You recently requested" when the person who initiated the email is not the same as the person that is receiving the email.
2. It calls out "your site" and doesn't say which site it's referring to until the end. Some people manage many sites.
3. "If this is correct, please click on the following link to change it" - Why would I change something that is correct? I understand it after thinking about it, but that's confusing.
4. Using terminology like approve and do not approve clarify the call to action.

[mark5454]

Please change my email address to markaustin823@… I am going to loose my old email address.

[garrett-eclipse]

Replying to mark5454:

Please change my email address to markaustin823@… I am going to loose my old email address.

Hi @mark5454 this thread is for core development, you can edit your profile here (while logged in);
​https://wordpress.org/support/users/mark5454/edit
*For further assistance please post to wordpress.org/support instead of this Core Trac

[Presskopp]

I think the wording can indeed be improved. Here's my proposal:

[TwisterMc]

It's great to see this moving forward! Thank you.

[peterwilsoncc]

Related #43706.

It also proposes changes to the new email message. Ideally both changes would go in to the same release to avoid doubling up the work for translators.

Trac ticket: https://core.trac.wordpress.org/ticket/45915

[audrasjb]

Tests are passing on the PR I added to refresh the patch. Self-assigning for commit.

[audrasjb]

In 53145:

Users: Improve wording of the "New Admin Email Address" email.

This changeset clarifies the email that the user gets when someone change the administration email address.

Props TwisterMc, Presskopp, audrasjb.
Fixes #45915.

committed in https://core.trac.wordpress.org/changeset/53145