Update PMM stable counterpart for CI/CD to Parker Ennis

Why is this change being made?

@parker_ennis Joined GitLab in January 2020, and will serve as the stable PMM counterpart for all of CI/CD. Updating our team page to reflect this.

Current PM/PMM Stable Counterparts for CI/CD

https://about.gitlab.com/handbook/product/categories/#cicd-section
https://about.gitlab.com/handbook/marketing/product-marketing/pmmteam/#which-product-marketing-manager-should-i-contact

• Continuous Integration: @jyavorska <> @williamchia
• Templates: @thaoyeager <> @williamchia
• Runner: @DarrenEastman <> @williamchia
• Testing: @jheimbuck_gl <> @williamchia
• Package: @trizzi <> @williamchia
• Progressive Delivery: @ogolowinski <> @williamchia
• Release Management: @jmeshell <> @williamchia

Proposed PM/PMM Stable Counterparts for CI/CD

https://trizzi-master-patch-07962.about.gitlab-review.app/handbook/product/categories/index.html#cicd-section
https://trizzi-master-patch-07962.about.gitlab-review.app/handbook/marketing/product-marketing/pmmteam/#which-product-marketing-manager-should-i-contact

• Continuous Integration: @jyavorska <> @parker_ennis
• Templates: @thaoyeager <> @parker_ennis
• Runner: @DarrenEastman <> @parker_ennis
• Testing: @jheimbuck_gl <> @parker_ennis
• Package: @trizzi <> @parker_ennis
• Progressive Delivery: @ogolowinski <> @parker_ennis
• Release Management: @jmeshell <> @parker_ennis