Make configure_for_func_testing compatible with e.g. Centos

In the configure_for_func_testing script openvswitch is installed
from source. We need to set proper flag (Q_BUILD_OVS_FROM_GIT) which
is used in Devstack to tell Devstack to install it from source and
not from packages.

This patch also removes flag BUILD_OVS_FROM_SOURCE from the
configure_for_func_testing file as it was only used in that file
and was actually duplicating the Q_BUILD_OVS_FROM_GIT option used also
in Devstack.

This patch also combines changes from [1] as it is also required to make
all those jobs working fine.

[1] https://review.opendev.org/c/openstack/neutron/+/824924

Conflicts:
    tools/configure_for_func_testing.sh

Change-Id: I09c79d0e9700cc2bfdf71e5314ea660de75ac1d3
(cherry picked from commit 391726bd4c)

roles/configure_functional_tests/tasks/main.yaml

@@ -15,6 +15,7 @@
         STACK_USER=stack
         OVS_BRANCH={{ OVS_BRANCH }}
         OVN_BRANCH={{ OVN_BRANCH }}
+        Q_BUILD_OVS_FROM_GIT={{ Q_BUILD_OVS_FROM_GIT }}
 
         source $DEVSTACK_PATH/functions
         source $DEVSTACK_PATH/lib/neutron_plugins/ovn_agent

tools/configure_for_func_testing.sh

@@ -62,8 +62,8 @@ NEUTRON_DIR=${NEUTRON_DIR:=$REPO_BASE/$PROJECT_NAME}
 INSTALL_MYSQL_ONLY=${INSTALL_MYSQL_ONLY:-False}
 # The gate should automatically install dependencies.
 INSTALL_BASE_DEPENDENCIES=${INSTALL_BASE_DEPENDENCIES:-$IS_GATE}
-BUILD_OVS_FROM_SOURCE=${BUILD_OVS_FROM_SOURCE:-True}
 OVN_BRANCH=${OVN_BRANCH:-master}
+Q_BUILD_OVS_FROM_GIT=${Q_BUILD_OVS_FROM_GIT:-True}
 OVS_BRANCH=${OVS_BRANCH:-master}
 
 
@@ -100,7 +100,7 @@ function _install_base_deps {
     echo_summary "Installing base dependencies"
 
     INSTALL_TESTONLY_PACKAGES=True
-    if [[ "$BUILD_OVS_FROM_SOURCE" == "True" ]]; then
+    if [[ "$Q_BUILD_OVS_FROM_GIT" == "True" ]]; then
         PACKAGES=$(get_packages general,neutron,q-agt,q-l3)
         # Do not install 'python-' prefixed packages other than
         # python-dev*.  Neutron's functional testing relies on deployment

zuul.d/base.yaml

@@ -28,6 +28,7 @@
       - ^rally-jobs/.*$
       - ^zuul.d/(?!(project)).*\.yaml
     vars:
+      Q_BUILD_OVS_FROM_GIT: True
       OVN_BRANCH: v21.06.0
       OVS_BRANCH: v2.16.0
       devstack_services:
@@ -50,6 +51,7 @@
     parent: neutron-functional
     vars:
       tox_envlist: dsvm-fullstack-gate
+      Q_BUILD_OVS_FROM_GIT: False
       zuul_copy_output:
         # We need to copy directory with logs to have it in job artifacts also,
         # /opt/stack/logs is default logs directory defined in neutron's