Coding Standards: Remove unused `$tax` variable in `edit_term_link()`.

This changeset removes an unused variable assignment in `edit_term_link()`.

Props soean, mukesh27.
Fixes #64881.



git-svn-id: https://develop.svn.wordpress.org/trunk@62045 602fd350-edb4-49c9-b593-d223f7449a82