Improve the OpenSearch Dashboards release process to add coverage and certify browser/device matrix

[seraphjiang]

Is your feature request related to a problem? Please describe.

There were issue in 2.7 release, mobile view for Dashboards broke after update to 2.7.0. There is no browser/viewport specific automation in release process. The regression test are best effort depends on each code author of PR.

1. in observability plugin Remove styling causing issue for banner in advanced settings dashboards-observability#488
3. in core [CCI] Fix bottom bar visibility using createPortal #3978

Describe the solution you'd like

We are seeking for a solution which could adding automation test to certify supported browser/device(Desktop, Tablet, Mobile)

Describe alternatives you've considered

could we evaluate what options we have to make it automation.

https://www.cypress.io/blog/2020/07/08/end-to-end-testing-mobile-apps-with-ionic-and-cypress/