A recent change in os-brick [1], which is used by cinder backends,
requires external file locks. This patch adds support for configuring
the lock path, with a default value that matches the corresponding
lock paths used by other services that use os-brick (namely cinder
and nova).
[1] I6f7f7d19540361204d4ae3ead2bd6dcddb8fcd68
Closes-Bug: #1980539
Change-Id: I5ea6766656f4227a1c514777c03bbf78d4ac59cd
(cherry picked from commit 6f61ecd9c5)
(cherry picked from commit ba4ada0c70)
(cherry picked from commit 1d37e5400a)