docs(microservices): enhance Kafka retry handling documentation

[gkdis6]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/docs.nestjs.com/blob/master/CONTRIBUTING.md

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Docs
• Other... Please describe:

What is the current behavior?

• Connection-level retry configuration examples
• Sophisticated message-level retry handling with circuit breaker pattern
• Examples of different retry configurations per event handler
• Consistent documentation style with other NestJS docs

Issue Number: #14930

What is the new behavior?

• Add connection-level retry configuration example
• Implement circuit breaker pattern for message-level retry
• Add per-event handler retry configuration example
• Improve documentation style consistency

Does this PR introduce a breaking change?

• Yes
• No