Remove 'gabbi_tempest_path' from devstack-tempest job

We need to move 'gabbi_tempest_path' var to gabbi-tempest plugin jobs side
which is the only place it is being used. This var is specific to gabbi-tempest
not used for any other devstack-tempest jobs so defining it in devstack-tempest
base job is not the correct way. We might face issue like bug#1821072 again in
future which can end up blocking all gate jobs.

Below patch is moving this var to gabbi-tempest plugin.
- https://review.opendev.org/#/c/705339/

Change-Id: Id96e9b3f1271fce50aae982fdf12871693107e1d
Closes-Bug: #1861592
diff --git a/playbooks/devstack-tempest-ipv6.yaml b/playbooks/devstack-tempest-ipv6.yaml
index 5f72345..4788362 100644
--- a/playbooks/devstack-tempest-ipv6.yaml
+++ b/playbooks/devstack-tempest-ipv6.yaml
@@ -7,11 +7,6 @@
 
 # We run tests only on one node, regardless how many nodes are in the system
 - hosts: tempest
-  environment:
-    # This enviroment variable is used by the optional tempest-gabbi
-    # job provided by the gabbi-tempest plugin. It can be safely ignored
-    # if that plugin is not being used.
-    GABBI_TEMPEST_PATH: "{{ gabbi_tempest_path | default('') }}"
   roles:
     - setup-tempest-run-dir
     - setup-tempest-data-dir
diff --git a/playbooks/devstack-tempest.yaml b/playbooks/devstack-tempest.yaml
index 4539bf9..3b969f2 100644
--- a/playbooks/devstack-tempest.yaml
+++ b/playbooks/devstack-tempest.yaml
@@ -7,11 +7,6 @@
 
 # We run tests only on one node, regardless how many nodes are in the system
 - hosts: tempest
-  environment:
-    # This enviroment variable is used by the optional tempest-gabbi
-    # job provided by the gabbi-tempest plugin. It can be safely ignored
-    # if that plugin is not being used.
-    GABBI_TEMPEST_PATH: "{{ gabbi_tempest_path | default('') }}"
   tasks:
     - name: Setup Tempest Run Directory
       include_role:
diff --git a/tox.ini b/tox.ini
index 2ea8129..d8e059a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -23,7 +23,7 @@
     OS_STDERR_CAPTURE=1
     OS_TEST_TIMEOUT=160
     PYTHONWARNINGS=default::DeprecationWarning,ignore::DeprecationWarning:distutils,ignore::DeprecationWarning:site
-passenv = OS_STDOUT_CAPTURE OS_STDERR_CAPTURE OS_TEST_TIMEOUT OS_TEST_LOCK_PATH TEMPEST_CONFIG TEMPEST_CONFIG_DIR http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY ZUUL_CACHE_DIR REQUIREMENTS_PIP_LOCATION GENERATE_TEMPEST_PLUGIN_LIST GABBI_TEMPEST_PATH
+passenv = OS_STDOUT_CAPTURE OS_STDERR_CAPTURE OS_TEST_TIMEOUT OS_TEST_LOCK_PATH TEMPEST_CONFIG TEMPEST_CONFIG_DIR http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY ZUUL_CACHE_DIR REQUIREMENTS_PIP_LOCATION GENERATE_TEMPEST_PLUGIN_LIST
 usedevelop = True
 install_command = pip install {opts} {packages}
 whitelist_externals = *