Remove .wp-login-logo class as it is unused

[im3dabasia1]

The .wp-login-logo class was introduced in a prior changeset #59138 (6.7) but the corresponding CSS selectors were reverted in a subsequent changeset #59424 (6.7.1). As a result, the class is no longer used in any .css files in the WordPress core. I propose removing this unused class from the HTML markup for cleaner code.

Trac ticket: https://core.trac.wordpress.org/ticket/62609

The .wp-login-logo class is no longer used in any CSS files within WordPress Core. This PR removes the unused class from the HTML markup to improve code clarity and maintainability.

[im3dabasia1]

Sharing a screenshot showing no CSS linked to the .wp-login-logo class:

It doesn’t cause any harm, so we can leave it? WDYT @joedolson

[TobiasBg]

The class might now be used by people that needed a quick solution to restore broken login logos after the release of WP 6.7 and before the release of WP 6.7.1.
These solutions might break again if the class is removed, which therefore would be a backward-compatibility break.

Due to this, the class should probably stay.

[joedolson]

I think we should leave this in place; both for the same reason that @TobiasBg suggested, but also because I think it's a benefit to have this specific selector available.

I'm going to close this as wontfix; feel free to re-open if you think it needs more discussion.