KAFKA-19981: Handle retriable remote storage exception in RemoteLogManager

[DL1231]

This PR distinguishes between RemoteStorageException and
RetriableRemoteStorageException in RemoteLogManager to handle
temporary storage degradations gracefully:

1. Copy path: Avoids deleting partially uploaded segments when
   RetriableRemoteStorageException is thrown;
2. Delete path: Skips incrementing failedRemoteDeleteRequestRate metric
   for retriable exceptions;
3. Documentation: Updates RemoteStorageManager Javadoc to clarify
   exception usage;
4. Testing: Adds UT for retriable scenarios.

[kamalcph]

Thanks for the patch! It looks good to me.

We can further update the RemoteLogManager javadoc to convey the contract to the plugin implementor.

@showuon Could you also review this PR? More details are on the ticket: KAFKA-19981. We want to take different actions in Kafka based on the error thrown by the plugin. Let me know your thoughts. Thanks!