When repairing a partition with many rows, we can store many fragments
in a repair_row_on_wire object which is sent as a rpc stream message.
This could cause reactor stalls when the rpc stream compression is
turned on, because the compression compresses the whole message without
any split and compression.
This patch solves the problem at the higher level by reducing the
message size that is sent to the rpc stream.
Tests are added to make sure the message split works.
Fixes#24808
e28c75aa79