Make sure LVM config is updated before running pvcreate
Make sure LVM config is updated before running pvcreate

Our internal "global" LVM config is set during reset() but we have
test cases that run pvcreate without running reset() first so we
need to make sure to update the global config before running it
because the config string now also controls whether the new LVM
devices file will be used or not.

rvykydal/blivet,vojtechtrefny/blivet,vojtechtrefny/blivet,rvykydal/blivet