LAVA: Automatically derive (userdata) image paths

This sets conventions on where userdata images prepared for automation
are to be located on the LAVA hosts for specific device models and
Android versions.

Also start generalizing paths for other images regarding the device
type.

Issue: INFRA-30
Issue: INFRA-141
Change-Id: I058dc9d1d9fbf617a0dbf47e56ae3c822852eb28
diff --git a/lava/templates/partials/multinode-worker-share-device.yaml b/lava/templates/partials/multinode-worker-share-device.yaml
index f78aa33..f273a9b 100644
--- a/lava/templates/partials/multinode-worker-share-device.yaml
+++ b/lava/templates/partials/multinode-worker-share-device.yaml
@@ -43,7 +43,7 @@
         BOOT_TIMEOUT_SECS: "480"
         NETWORK_TIMEOUT_SECS: "300"
         ADB_CONNECT_TEST_TIMEOUT_SECS: "60"
-        USERDATA_IMAGE_FILE: "{{ userdata_image_file }}"
+        USERDATA_IMAGE_FILE: "/lava-lxc/userdata.img"
 
 - test:
     namespace: tlxc