Remove includes and parameter functions

We no longer are support parameter functions and includes for zuulv3.
However, we may reclaim includes in the future so we can support raw
inclusions, so everything does not have to be in one file.

Story: #2000784

Change-Id: I58608ae564a890bca19eef63d9ae73fa388adf39
Signed-off-by: Paul Belanger <pabelanger@redhat.com>
diff --git a/doc/source/launchers.rst b/doc/source/launchers.rst
index 78d5839..8a8c932 100644
--- a/doc/source/launchers.rst
+++ b/doc/source/launchers.rst
@@ -273,9 +273,7 @@
   build:FUNCTION_NAME:NODE_NAME
 
 where **NODE_NAME** is the name or class of node on which the job
-should be run.  This can be specified by setting the ZUUL_NODE
-parameter in a parameter-function (see :ref:`includes` section in
-:ref:`zuulconf`).
+should be run.
 
 Zuul sends the ZUUL_* parameters described in `Zuul Parameters`_
 encoded in JSON format as the argument included with the
diff --git a/doc/source/zuul.rst b/doc/source/zuul.rst
index 102beac..ad6a061 100644
--- a/doc/source/zuul.rst
+++ b/doc/source/zuul.rst
@@ -261,26 +261,6 @@
 Zuul should perform.  There are three sections: pipelines, jobs, and
 projects.
 
-.. _includes:
-
-Includes
-""""""""
-
-Custom functions to be used in Zuul's configuration may be provided
-using the ``includes`` directive.  It accepts a list of files to
-include, and currently supports one type of inclusion, a python file::
-
-  includes:
-    - python-file: local_functions.py
-
-**python-file**
-  The path to a python file (either an absolute path or relative to the
-  directory name of :ref:`layout_config <layout_config>`).  The
-  file will be loaded and objects that it defines will be placed in a
-  special environment which can be referenced in the Zuul configuration.
-  Currently only the parameter-function attribute of a Job uses this
-  feature.
-
 Pipelines
 """""""""
 
@@ -800,33 +780,6 @@
 
 **tags (optional)**
   A list of arbitrary strings which will be associated with the job.
-  Can be used by the parameter-function to alter behavior based on
-  their presence on a job.  If the job name is a regular expression,
-  tags will accumulate on jobs that match.
-
-**parameter-function (optional)**
-  Specifies a function that should be applied to the parameters before
-  the job is launched.  The function should be defined in a python file
-  included with the :ref:`includes` directive.  The function
-  should have the following signature:
-
-  .. function:: parameters(item, job, parameters)
-
-     Manipulate the parameters passed to a job before a build is
-     launched.  The ``parameters`` dictionary will already contain the
-     standard Zuul job parameters, and is expected to be modified
-     in-place.
-
-     :param item: the current queue item
-     :type item: zuul.model.QueueItem
-     :param job: the job about to be run
-     :type job: zuul.model.Job
-     :param parameters: parameters to be passed to the job
-     :type parameters: dict
-
-  If the parameter **ZUUL_NODE** is set by this function, then it will
-  be used to specify on what node (or class of node) the job should be
-  run.
 
 **swift**
   If :ref:`swift` is configured then each job can define a destination