### What changes were proposed in this pull request?
This is a follow-up to #29855 according to the [comments](https://github.com/apache/spark/pull/29855/files#r505536514)
In this PR, the following changes are made:
1. A new `BlockPushingListener` interface is created specifically for block push. The existing `BlockFetchingListener` interface is left as is, since it might be used by external shuffle solutions. These 2 interfaces are unified under `BlockTransferListener` to enable code reuse.
2. `RetryingBlockFetcher`, `BlockFetchStarter`, and `RetryingBlockFetchListener` are renamed to `RetryingBlockTransferor`, `BlockTransferStarter`, and `RetryingBlockTransferListener` respectively. This makes their names more generic to be reused across both block fetch and push.
3. Comments in `OneForOneBlockPusher` are further clarified to better explain how we handle retries for block push.
### Why are the changes needed?
To make code cleaner without sacrificing backward compatibility.
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
Existing unit tests.
Closes#33340 from Victsm/SPARK-32915-followup.
Lead-authored-by: Min Shen <mshen@linkedin.com>
Co-authored-by: Min Shen <victor.nju@gmail.com>
Signed-off-by: Mridul Muralidharan <mridul<at>gmail.com>
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