Revert "Bump scanner THREADS to 10 by default"

This reverts commit f537f91943.

lib/msf/core/auxiliary/scanner.rb

@@ -18,7 +18,7 @@ def initialize(info = {})
 
   register_options([
       OptAddressRange.new('RHOSTS', [ true, "The target address range or CIDR identifier"]),
-      OptInt.new('THREADS', [ true, "The number of concurrent threads", 10 ] )
+      OptInt.new('THREADS', [ true, "The number of concurrent threads", 1 ] )
     ], Auxiliary::Scanner)
 
   # RHOST should not be used in scanner modules, only RHOSTS

lib/msf/core/auxiliary/udp_scanner.rb

@@ -23,6 +23,7 @@ module Auxiliary::UDPScanner
     [
       Opt::RPORT,
       OptInt.new('BATCHSIZE', [true, 'The number of hosts to probe in each set', 256]),
+      OptInt.new('THREADS', [true, "The number of concurrent threads", 10])
     ], self.class)
 
     register_advanced_options(