Fix reported issues

Some issues were reported in comments from T5439.
This patch fixes them.

Signed-off-by: Frédéric Dalleau <frederic.dalleau@collabora.com>

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

@@ -69,7 +69,9 @@ run:
         >bootcount=1
         bootlimit=3
         upgrade_available=1
-    - "Reset the DUT 3 times before the boot finishes"
+    - "Restart the device by pressing the restart button before the boot finishes."
+    - "Restart the device a second time by pressing the restart button before the boot finishes."
+    - "Restart the device a third time by pressing the restart button before the boot finishes."
     - "U-Boot should be able to detect the rollback mode and boot the system in rollback mode"
     - |
         >Warning: Bootlimit (3) exceeded. Using altbootcmd.

test-cases/apertis-update-manager-usb-unplug.yaml

@@ -50,12 +50,11 @@ run:
     - $ sudo journalctl -ef --unit apertis-update-manager &
     - "Plug the USB flash drive into the device"
     - "The update starts automatically"
-    - "Wait while the upgrade starts and remove the USB flash before it is completed, as described below"
+    - "Wait while the upgrade starts (5-20 seconds depending on your HW) and remove the USB flash drive before it is completed:"
     - |
         >Dec 19 22:31:46 apertis apertis-update-[390]: mount added : /media/test
         Dec 19 22:31:46 apertis apertis-update-[390]: Ostree static delta starting
         Dec 19 22:31:46 apertis apertis-update-[390]: Cannot check the ID in black list: No such file or directory
-    - "Wait 5-20 seconds (depending on your HW) and remove the USB flash drive"
     - "Update should be interrupted with error messages similar to"
     - |
         >[   59.542717] scsi 1:0:0:0: rejecting I/O to offline device