build: make 'floating patch' message informational

Downgrade the 'Using floating patch' message that is emitted
when a local patch is applied to the bundled ICU from a warning
to a notice. There isn't anything the user can or should do so
warning isn't appropriate. Instead of angry yellow use soothing green.

Fixes: https://github.com/nodejs/node/issues/26346

PR-URL: https://github.com/nodejs/node/pull/26349


Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>