Fix overwriting of low-level Kafka options with auth options

[lxnewayfarer]

Context

There was a problem with Kafka authorization due to the fact that the auth options overwritten the low-level kafka_config options. As a result, we could not use SASL_SSL authorization with an SSL certificate.
I fixed the line where the Kafka configuration was overwritten with the default authorization options. This looks more logical, and makes it possible to configure the connection to Kafka through the low-level config.

What's inside

• The ability to configure auth for connecting to Kafka through the low-level config
• Fix pipeline uninitialized constant ActiveSupport::LoggerThreadSafeLevel::Logger error in the spec/rails_helper.rb on older versions of Rails. Solution: Ensure the logger gem is loaded in Rails 7.0 rails/rails#54264 (comment)
  Failed job example: https://github.com/lxnewayfarer/sbmt-kafka_producer/actions/runs/12985571892/job/36210696308

Checklist:

• I have added tests
• I have made corresponding changes to the documentation

[bibendi]

Hi! Thanks for the PR! It seems that the more correct solution would be to refine the auth config so that it understands SASL_SSL authorization. But nevertheless, definitely the auth section should certainly not overwrite low-level options. I think, we should keep this fix.

[lxnewayfarer]

@bibendi can you please tell me when it can be expected to be merged?