MAINTAINERS: fix a bunch of directory paths

Fix various incorrect maintainer file entry for directories. These
are currently matching files, but would break few scripts if we were to
upgrade the CI image to Python 3.11 due to a change in behavior of
Path.glob().

Fixes various:

MAINTAINERS.yml: glob pattern '...' in 'files' in area '...' does not
match any files

on machines running Python 3.11 or newer.

Link: https://docs.python.org/3/library/pathlib.html#pathlib.Path.glob


Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>