refactor(pipelines/pingcap/ticdc): optimize ticdc pipelines for resource efficiency (#4109)
This PR optimizes the TiCDC integration test pipelines in `pipelines/pingcap/ticdc/latest/` to improve resource efficiency and consistency.
## The following changes were made
**Classic Pipelines:**
1. For `pull_cdc_kafka_integration_light` and `pull_cdc_mysql_integration_light`, the pipelines were refactored to: - Use `agent none` at the pipeline level. - Merge the `Checkout` and `prepare` stages into a single `Checkout & Prepare` stage with its own agent. This ensures agents are only allocated when required.
2. For `pull_cdc_kafka_integration_heavy`, `pull_cdc_mysql_integration_heavy`, `pull_cdc_pulsar_integration_light`, `pull_cdc_storage_integration_heavy`, and `pull_cdc_storage_integration_light`, the redundant stage-level `timeout` option was removed from the `Checkout & Prepare` stage. This centralizes timeout management at the global pipeline level.
**Next-gen Pipelines:**
All `next_gen` integration test pipelines were refactored to: - Use `agent none` at the pipeline level. - Merge the `Checkout` and `prepare` stages into a single `Checkout & Prepare` stage with its own agent.
This aligns the `next_gen` pipelines with the resource-saving standards of the classic pipelines, ensuring that agents are only allocated when required. This reduces overall resource consumption and improves maintainability.
