Add prefix MAESTRO_ to Maestro env variable.

.maestro/tests/roomList/createAndDeleteDM.yaml

@@ -1,11 +1,11 @@
-appId: ${APP_ID}
+appId: ${MAESTRO_APP_ID}
 ---
 # Purpose: Test the creation and deletion of a DM room.
 - tapOn: "Create a new conversation or room"
 - tapOn: "Search for someone"
-- inputText: ${INVITEE1_MXID}
+- inputText: ${MAESTRO_INVITEE1_MXID}
 - tapOn:
-    text: ${INVITEE1_MXID}
+    text: ${MAESTRO_INVITEE1_MXID}
     index: 1
 - takeScreenshot: build/maestro/330-createAndDeleteDM
 - tapOn: "maestroelement2"