meta: move Glen Keane to Collaborator Emeritus

In email, Glen confirmed that he is happy to move to Emeritus. He also
informed me that his handle is no longer thekemkid and is now glentiki.
At his request, I've updated the handle in the README in addition to
moving him to Emeritus.

PR-URL: https://github.com/nodejs/node/pull/31993


Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>