readOnly means socketPath can only ever hold the default, so the fixture's
old custom value can no longer reach the unit and the check.module-eval
assertion for it was failing. Assert the default instead of deleting the
check -- it still catches the env var vanishing or being misspelled, which
deleting it would not.
Also corrects the block's stale 'FOUR movers' count: socketPath lost its
pre-rename shim in the same slice, so only three of the asserted values
are still rename-shim movers.
b590038b0f