Unlimited memory consumption in `RepartitionExec`

**Describe the bug**
See https://github.com/apache/arrow-datafusion/blob/5b70e3543f5c10832e43ed25e7d4166cf0c1df78/datafusion/core/src/physical_plan/repartition.rs#L333-L340

**To Reproduce**
\-

**Expected behavior**
The data kept in these channels should be registered with the `MemoryManager`.

**Additional context**
\-
