migration: Rename save_live_complete_precopy to save_complete

Now after merging the precopy and postcopy version of complete() hook,
rename the precopy version from save_live_complete_precopy() to
save_complete().

Dropping the "live" when at it, because it's in most cases not live when
happening (in precopy).

No functional change intended.

Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250613140801.474264-7-peterx@redhat.com
[peterx: squash the fixup that covers a few more doc spots, per Juraj]
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
9 files changed