Changes

TiCDC: Increase memory limits for TiCDC integration test pods to 24Gi (#4094)

## Increase Memory Limits for TiCDC Integration Tests

This pull request increases the memory resource limits for several TiCDC
integration test pipelines to improve stability and prevent
out-of-memory (OOM) failures during heavy workload testing.

### Why This Change Is Needed
Recent test runs have shown intermittent failures in heavy integration
tests due to memory exhaustion. The current 16Gi limit is insufficient
for handling peak loads during complex data replication scenarios
involving Kafka and storage integrations. Increasing the memory limit to
24Gi will provide a more stable testing environment and reduce flaky
test results.

### Changes Made
- Updated memory limits from `16Gi` to `24Gi` in four integration test
configurations:
  - `pull_cdc_kafka_integration_heavy/pod-test.yaml`
  - `pull_cdc_kafka_integration_heavy_next_gen/pod-test.yaml`
  - `pull_cdc_storage_integration_heavy/pod-test.yaml`
  - `pull_cdc_storage_integration_heavy_next_gen/pod.yaml`

### Impact
- CPU limits remain unchanged at 6 cores
- No changes to test logic or container images
- Only resource allocation adjustments for improved reliability
- Should reduce OOM-related test failures in CI/CD pipelines

This change ensures our integration tests can run more reliably under
heavy workloads, providing better confidence in TiCDC's performance and
stability.

Signed-off-by: tenfyzhong <tenfy@tenfy.cn>
 (commit: 42f7d02)