Changes

fix(ticdc): increase kafka container resources (#3967)

This pull request updates several Kafka integration test pipeline
configurations to improve performance and reliability. The main changes
include increasing resource allocations for Kafka containers and
explicitly setting the Kafka log directory across multiple test YAML
files.

Resource configuration improvements:

* Increased CPU and memory requests and limits for the Kafka container
from `2000m`/`6Gi` to `4000m`/`12Gi` in
`pod-pull_cdc_kafka_integration_heavy.yaml`,
`pull_cdc_kafka_integration_heavy_next_gen/pod-test.yaml`, and
`pod-pull_cdc_integration_kafka_test.yaml`.
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Environment variable additions:

* Added the `KAFKA_LOG_DIRS` environment variable with the value
`/tmp/tidb_cdc_test` to all relevant pipeline YAML files, ensuring
consistent Kafka log storage location.
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 (commit: b521b64)