Page: tabIndex default value (mainTabIndex=-1) which prevents keyboard scroll

Describe the issue. What is the expected and unexpected behavior?
mainTabIndex=-1 as a default value prevents keyboard scroll. tlabindex should be removed. Having a tabindex on a container essentially breaks focus and keyboard scroll for all non-focusable containers below it. eg topology details side panel.

Any contributions to the main content should not have to deal with adding their own tabindex attribute to their scroll containers.

Above notes from the pr: https://github.com/openshift/console/pull/9140#issuecomment-854134911

workaround is to set the mainTabIndex to null.

Please provide the steps to reproduce. Feel free to link CodeSandbox or another tool.

https://github.com/openshift/console/pull/9140#issuecomment-8541349113

Is this a bug or enhancement? If this issue is a bug, is this issue blocking you or is there a work-around?
Bug
What is your product and what release version are you targeting?
OpenShift 4.9

Start with the referenced PatternFly React pull request #9140 and its linked issue comment to locate the mainTabIndex default. Remove the default tabindex behavior, then verify that keyboard scrolling works for non-focusable containers without requiring a mainTabIndex workaround.