Rename apertis-update-manager-automount to match filename

Use apertis-update-manager-automount for the test case name so it
matches its filename.

Signed-off-by: Luis Araujo <luis.araujo@collabora.co.uk>

test-cases/apertis-update-manager-automount.yaml

 metadata:
-  name: apertis-update-manager-auto
+  name: apertis-update-manager-automount
   format: "Apertis Test Definition 1.0"
   image-types:
     minimal: [ armhf ]