Fix "two heros" problem in CI/CD > Pipelines when no pipelines and Auto DevOps banner

Description

Decoupling from https://gitlab.com/gitlab-org/gitlab-ce/issues/38587, so we can prioritize earlier.

In CI/CD > Pipelines, when the empty state and Auto DevOps banner are shown at the same time, we have a "two heros" problem where two primary buttons are shown (one for the banner, one for the empty state).

See original comment in https://gitlab.com/gitlab-org/gitlab-ce/issues/38587:

Auto devops vs empty state

1. This should be tackled in a different issue
2. What we should do for this issue, is make it so that the button on the banner is a secondary outlined button.