airskiff: Remove CI OSH-infra relative path

Since [0] updated the Airskiff CI jobs to clone dependent projects, the
relative OSH-infra path for the airskiff job no longer exists. This
change removes it so that the CI can use the cloned path as specified in
the airskiff deployment scripts.

[0] https://review.opendev.org/651628

Change-Id: Idc6970c3048f0e2bcf2fabcf79693973bde3f389

.zuul.yaml

@@ -103,8 +103,6 @@
       - tools/gate/playbooks/airskiff-reduce-site.yaml
     run: tools/gate/playbooks/airskiff-deploy-gate.yaml
     post-run: tools/gate/playbooks/debug-report.yaml
-    vars:
-      OSH_INFRA_PATH: "../../openstack/openstack-helm-infra"
     irrelevant-files:
       - ^.*\.rst$
       - ^doc/.*$

tools/gate/playbooks/airskiff-deploy-gate.yaml

@@ -29,7 +29,6 @@
 
     - name: Deploy Kubernetes with Minikube
       shell: |
-        export OSH_INFRA_PATH={{ OSH_INFRA_PATH }}
         ./tools/deployment/airskiff/developer/010-deploy-k8s.sh
       args:
         chdir: "{{ zuul.project.src_dir }}"