Remove stable/stein testing jobs

stable/stein is not suported in Tempest now, so
let's remove their jobs from master gate.

Also, update doc to reflect it.

Depends-On: https://review.opendev.org/c/openstack/stackviz/+/768212

Change-Id: I0cbc2883e1cfdb3b1d6b10a7ecea83a4bae32afb

doc/source/supported_version.rst

@@ -9,9 +9,9 @@ Compatible OpenStack Releases
 
 Tempest master supports the below OpenStack Releases:
 
+* Victoria
 * Ussuri
 * Train
-* Stein
 
 For older OpenStack Release:
 
@@ -34,3 +34,4 @@ Tempest master supports the below python versions:
 
 * Python 3.6
 * Python 3.7
+* Python 3.8

zuul.d/project.yaml

@@ -48,8 +48,6 @@
             irrelevant-files: *tempest-irrelevant-files
         - tempest-full-train-py3:
             irrelevant-files: *tempest-irrelevant-files
-        - tempest-full-stein-py3:
-            irrelevant-files: *tempest-irrelevant-files
         - tempest-multinode-full-py3:
             irrelevant-files: *tempest-irrelevant-files
         - tempest-tox-plugin-sanity-check:
@@ -139,7 +137,6 @@
         - tempest-full-victoria-py3
         - tempest-full-ussuri-py3
         - tempest-full-train-py3
-        - tempest-full-stein-py3
     periodic:
       jobs:
         - tempest-all

zuul.d/stable-jobs.yaml

@@ -15,9 +15,3 @@
     parent: tempest-full-py3
     nodeset: openstack-single-node-bionic
     override-checkout: stable/train
-
-- job:
-    name: tempest-full-stein-py3
-    parent: tempest-full-py3
-    nodeset: openstack-single-node-bionic
-    override-checkout: stable/stein