Acknowledge the reality of securityContext handling

[tdg5]

This has been touched on elsewhere, but I wanted to make it official to try to save other people time and confusion.

This PR does 2.5 things:

1. Cleans up trailing whitespace
2. Adds a coalesce that prioritizes taking securityContext config from .deployment.securityContext, but falls back to .securityContext to try to maintain existing mappings.
   1. I'd vote for removing the coalesce as part of 6.x release.
3. Replaces the unused default securityContext config with an empty object to try to maintain existing default configuration and be honest about what's really happening upon deployment.

If you disagree with any of these choices, let me know. Feedback is welcome.

Related:

• Invalid Pod securityContext Configuration (not sure why this was closed)
• fix: properly reference pod's securityContext from values and add deployment.securityContext.runAsNonRoot=true

[tdg5]

I verified against v5.1.1 that this does not work. The pod won't start with this config.