Auto-DevOps.gitlab-ci.yml : Upgrade helm in to 2.7.2
As a pre-requisite to https://gitlab.com/gitlab-org/gitlab-ce/issues/51338, we should upgrade helm to 2.7.2
As a pre-requisite to https://gitlab.com/gitlab-org/gitlab-ce/issues/51338, we should upgrade helm to 2.7.2