Fix Maestro logout test when the device is the only session

Since #7861 all the sessions of the Maestro account are ended after each run,
so the device under test is always the last session. In this case the title of
the sign out screen does not contain "Remove this device" anymore, and tapping
on the second occurrence of this text fails. Tap on the submit button using its
test tag instead.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

.maestro/tests/account/logout.yaml

@@ -13,14 +13,12 @@ appId: ${MAESTRO_APP_ID}
 - tapOn: "Cancel"
 - tapOn: "Remove this device"
 - tapOn:
-    text: "Remove this device"
-    index: 1
+    id: "sign-out-submit"
 # Cancel the dialog cancels the logout
 - tapOn:
     id: "dialog-negative"
 - tapOn:
-    text: "Remove this device"
-    index: 1
+    id: "sign-out-submit"
 - tapOn:
     id: "dialog-positive"
 - runFlow: ../assertions/assertInitDisplayed.yaml