Make error tracking payload less strict

What does this MR do?

The original schema was based on Rails SDK and was too strict (and web specific).

This MR makes validation schema less strict. SDK for different languages/frameworks can have certain fields missing. We should tolerate that.

Schema still validates fields we actually use in application so there is no change in behavior.

Issue #329596 (closed)

Does this MR meet the acceptance criteria?

Conformity

• [-] I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• [-] I have added/updated documentation, or it's not needed. (Is documentation required?)
• [-] I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• [-] I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.