POST module duplicate search results

Running a POST module in meterpreter was causing duplicate search
results for the executed module.  For example, running
post/windows/gather/checkvm would produce duplicate results for that
module when executing “search checkvm” in msf.

Debugging revealed that the cmd_exec function in meterpreter’s ui
command_dispatcher core was creating the specified module, and then
promptly reloading it.  The reload function was causing the duplicate
module_detail record to be written to the msg postgres database
instance.  Further analysis revealed that the “original_mod” could be
used for running the post module, so the “reloaded_mod” was removed
and the “original_mod” used in it’s place to run the post module.

SeeRM #8754