tests: qemuxmlconf: adjust test case to new virtiofsd

Now that we have a fake virtiofsd json descriptor in our vhost-user
test data, we can remove the explicitly specified binary and our
mocking will ensure this test won't be affected by the host state.

Also remove the locking options, since they were never supported
by the Rust version of virtiofsd.

Signed-off-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

tests/qemuxmlconfdata/vhost-user-fs-fd-memory.xml

@@ -28,10 +28,9 @@
     <controller type='pci' index='0' model='pci-root'/>
     <filesystem type='mount' accessmode='passthrough'>
       <driver type='virtiofs' queue='1024'/>
-      <binary path='/usr/libexec/virtiofsd' xattr='on'>
+      <binary xattr='on'>
         <cache mode='always'/>
         <sandbox mode='chroot'/>
-        <lock posix='off' flock='off'/>
         <thread_pool size='16'/>
       </binary>
       <idmap>