xfs: promote metadata directories and large block support

xfs: promote metadata directories and large block support

Large block support was merged upstream in 6.12 (Dec 2024) and metadata
directories was merged in 6.13 (Jan 2025).  We've not received any
serious complaints about the ondisk formats of these two features in the
past year, so let's remove the experimental warnings.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>