exchange: drop now-unnecessary "local" from lock name variables
Since fda0867cfe03 (exchange: drop support for lock-based unbundling
(BC), 2017-08-06), there is no more remote locking.
Differential Revision: https://phab.mercurial-scm.org/D390
#require docutils gettext $ $TESTDIR/check-gendoc pt_BR checking for parse errors