Use -x when testing help

MSP-11671

Instead of interactively typing `help` and `exit` use `-x` to run the
commands, which changes the average (n=10) time for `rake cucumber` from
153.29 seconds to an average (n=10) of 32.21 for a -78.99% change from
the last commit and a -80.47% change from the beginning of this branch
(3c3792330c).  Raw data:
https://docs.google.com/spreadsheets/d/1vCRi_38Go3Wfq670eDCXMTSSXL1blSbk6NQsgpOqfYw/edit?usp=sharing

features/commands/help.feature

@@ -1,12 +1,9 @@
 Feature: Help command
 
   Background:
-    Given I run `msfconsole --defer-module-loads` interactively
-    And I wait for stdout to contain "Free Metasploit Pro trial: http://r-7.co/trymsp"
+    Given I run `msfconsole --defer-module-loads -x help -x exit`
 
   Scenario: The 'help' command's output
-    When I type "help"
-    And I type "exit"
     Then the output should contain:
       """
       Core Commands