merge: disable stargz hardlinking
merge: disable stargz hardlinking

The stargz snapshotter creates separate FUSE mounts for each lazy
snapshot and non-FUSE mounts for newly created local snapshots. This
means that hardlinking during diffApply fails. The code then falls back
to doing a copy, which works fine, but it also results in a ton of debug
logs about the failing hardlinks to be printed. This change just results
in those noisy log lines no longer appearing.

Signed-off-by: Erik Sipsma <c195b508e6f0c57aeafdb5e96947e2b79e6a4b40@sipsma.dev>

tonistiigi/buildkit_poc,tonistiigi/buildkit_poc