Memory leaks when new owner is enabled

[overvenus]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do? If possible, provide a recipe for reproducing the error.

Capturing 6k tables, go runtime heap profile shows in_use objects leak with an acceleration 100k object/s^2.
Top memory consumers are:

• github.com/pingcap/ticdc/cdc/puller/sorter.runMerger.func2
  • model.NewResolvedPolymorphicEvent(0, ts) 10.8G
• github.com/pingcap/ticdc/cdc/processor/pipeline.(*sorterNode).Init.func4
  • pipeline.PolymorphicEventMessage(msg) 2.16G
• github.com/pingcap/ticdc/cdc/processor/pipeline.(*tablePipelineImpl).UpdateBarrierTs
  • pipeline.BarrierMessage(ts) 1.79G
• github.com/pingcap/ticdc/pkg/pipeline.NewPipeline.func1
  • TickMessage() 1.65G

In_use objects profile: https://gist.github.com/overvenus/af73663f299a71468e6c934dd9cabb8a

2. What did you expect to see?

No memory leak.

3. What did you see instead?

Memory leak.

4. Versions of the cluster

v5.0.3 with new owner.

[overvenus]

From heap profile, it shows that memory leak is caused by GC is slow, allocated objects (pipeline.Message) accumulate in memory.

[overvenus]

Testing TiCDC (together with #2226, #2415 and #2474) that captures 20k tables, no memory leak anymore, we can close the issue.