Fix inconsistency in config loading between Java and Go

[yolocs]

For a sample config

backend:
  remote:
    address: "" # empty

In Go, it will return an error saying address is required for a remote backend config.
In Java, it won't return an error; instead, it will treat that as a remote backend is not needed (enabled).

[capri-xiyue]

Do we need to fix such inconsistency?

[sethvargo]

I agree with @capri-xiyue - can we fix these inconsistencies instead of just documenting them?

[yolocs]

Yes, it would be preferable to completely fix the inconsistency. But there are 1) technical viability 2) language idiomaticity to consider. For this one, I agree we should just fix it. Renaming the title.

[sqin2019]

In addition to remote backend config, other inconsistencies:

• cloudlogging set default logic
• locallogging missing in go side, existing issue
• go side missing LogType Unspecified
• when security_context is not nil, go client require nonnil and nonempty security_context key where java only require nonnil security_context.
• not sure if regex can be nil when filter related env vars are set.