Script Loader: Change the `jquery` handle back to an alias for `jquery-core`.

This ensures that `wp_localize_script( 'jquery', ... )` continues to work as expected, since `WP_Scripts::localize()` rewrites the `jquery` handle to `jquery-core` internally.

Follow-up to [48323].

Props mukesh27, rajeshsingh520, johnbillion, TimothyBlynJacobs, TobiasBg.
Merges [48890] to the 5.5 branch.
Fixes #50919.
Built from https://develop.svn.wordpress.org/branches/5.5@48891


git-svn-id: https://core.svn.wordpress.org/branches/5.5@48653 1a063a9b-81f0-0310-95a4-ce76da25c4cd