cbuildbot: delete unused paygen code

Nothing uses this anymore, so delete it all.

BUG=None
TEST=CQ passes

Change-Id: I4626970d373c060e0e2bd1e7d9e819bc2fb44e4c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4682865
Reviewed-by: George Engelbrecht <engeg@google.com>
Reviewed-by: Jae Hoon Kim <kimjae@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/scripts/cbuildbot.py b/scripts/cbuildbot.py
index 775453f..3597279 100644
--- a/scripts/cbuildbot.py
+++ b/scripts/cbuildbot.py
@@ -531,13 +531,6 @@
         ),
     )
     group.add_remote_option(
-        "--nopaygen",
-        action="store_false",
-        dest="paygen",
-        default=True,
-        help="Don't generate payloads.",
-    )
-    group.add_remote_option(
         "--noreexec",
         action="store_false",
         dest="postsync_reexec",
@@ -948,20 +941,13 @@
         )
 
     build_config = site_config[options.build_config_name]
-    is_payloads_build = build_config.build_type == constants.PAYLOADS_TYPE
 
-    if options.channels and not is_payloads_build:
+    if options.channels:
         cros_build_lib.Die(
             "--channel must only be used with a payload config,"
             " not target (%s)." % options.build_config_name
         )
 
-    if not options.channels and is_payloads_build:
-        cros_build_lib.Die(
-            "payload configs (%s) require --channel to do anything useful."
-            % options.build_config_name
-        )
-
     # If the build config explicitly forces the debug flag, set the debug flag
     # as if it was set from the command line.
     if build_config.debug: