Remove grenade-heat and tripleo experimental jobs

This patch propose to remove following two jobs:

* grenade-heat:
    Since we also run grenade-heat-multinode job, I don't think of any
reason to run both all in one version and multinode version.

* tripleo-ci-centos-7-scenario002-standalone:
    This is an experimental job which I don't think it's required by
Tripleo anymore since it's not been triggered for a while [1].

[1] https://zuul.openstack.org/builds?
job_name=tripleo-ci-centos-7-scenario002-standalone#

Change-Id: I081d2656eb2f20501b20e267afd19b91c73bd39a

.zuul.yaml

@@ -137,8 +137,12 @@
         HEAT_USE_MOD_WSGI: False
 
 - job:
-    name: grenade-heat
+    name: grenade-heat-multinode
     parent: legacy-dsvm-base
+    nodeset: ubuntu-bionic-2-node
+    roles:
+      - zuul: zuul/zuul-jobs
+    pre-run: playbooks/devstack/multinode-networking/pre.yaml
     run: playbooks/devstack/grenade/run.yaml
     post-run: playbooks/devstack/grenade/post.yaml
     timeout: 7800
@@ -156,19 +160,9 @@
       - ^heat/tests/.*$
       - ^releasenotes/.*$
       - ^setup.cfg$
-    vars:
-      topology: aio
-      branch_override: default
-
-- job:
-    name: grenade-heat-multinode
-    parent: grenade-heat
-    nodeset: ubuntu-bionic-2-node
-    roles:
-      - zuul: zuul/zuul-jobs
-    pre-run: playbooks/devstack/multinode-networking/pre.yaml
     vars:
       topology: multinode
+      branch_override: default
 
 - project:
     templates:
@@ -181,7 +175,6 @@
       - release-notes-jobs-python3
     check:
       jobs:
-        - grenade-heat
         - grenade-heat-multinode
         - heat-functional
         - heat-functional-legacy
@@ -189,10 +182,6 @@
     gate:
       queue: heat
       jobs:
-        - grenade-heat
         - grenade-heat-multinode
         - heat-functional
         - heat-functional-legacy
-    experimental:
-      jobs:
-        - tripleo-ci-centos-7-scenario002-standalone