[jaeger-v2]: Fix Kafka E2E Test To Use Default Environment Variables

[mahadzaryab1]

Problem

• Part of [jaeger-v2] Rethink components configuration to align with OTEL #5229
• [jaeger-v2] Rethink components configuration to align with OTEL #5229 (comment) summarizes the problem that we want to solve nicely

[mahadzaryab1]

@yurishkuro Would you be able to help me understand why we needed createConfigWithEncoding? Why could we not just create configuration files that had the desired values that we needed?

[yurishkuro]

Because we want to test the one official config we provide, not create copies of it that may become out of date.

[mahadzaryab1]

@yurishkuro got it! and does setting the environment variable take precedent over the config in the YAML file?

[yurishkuro]

It does not. If config has a fixed value the env variable is not going to affect it. Previously you could reference env variable from the config, but then you always have to provide the variable, otherwise the config is invalid. Now you could have both - a default value and a way to override it via env variable.

[mahadzaryab1]

It does not. If config has a fixed value the env variable is not going to affect it. Previously you could reference env variable from the config, but then you always have to provide the variable, otherwise the config is invalid. Now you could have both - a default value and a way to override it via env variable.

@yurishkuro Thanks for the explanation! PR is ready for review at #6028.