sim:tests: workaround uart prompt ambiguity

Wait for "EOF" instead of "CANTRIP>" at bootup so the checkpoint happens
after "source autostart.repl" completes.

Change-Id: I4fce710558f821ff2dd194168ca387588a209ab3
diff --git a/shodan_boot.robot b/shodan_boot.robot
index df45c85..8077370 100644
--- a/shodan_boot.robot
+++ b/shodan_boot.robot
@@ -98,7 +98,7 @@
     Prepare Machine
     Start Emulation
     Create Terminal Tester      ${UART5}
-    Wait For Prompt On Uart     ${PROMPT}
+    Wait For Prompt On Uart     EOF
     # The following commented lines would cause the test failed to be saved.
     Provides                    shodan-bootup
 
diff --git a/shodan_stress.robot b/shodan_stress.robot
index b2fbefb..0b96c76 100644
--- a/shodan_stress.robot
+++ b/shodan_stress.robot
@@ -53,7 +53,7 @@
     Prepare Machine
     Start Emulation
     Create Terminal Tester      ${UART5}
-    Wait For Prompt On Uart     ${PROMPT}
+    Wait For Prompt On Uart     EOF
 
     FOR    ${iter}    IN RANGE    ${MAX_ITER}
       IF     ${{random.randint(0, 2)}} == 0