PoC: Raise error for Gitaly streamed responses w/o blocks
What does this MR do?
That's a PoC for #30334 (closed).
The idea is raising an error when GitalyClient.call is used to call an RPC that returns a streamed response without a block. In my point of view we could make GitalyClient.call require a block being given when we know the response is streamed, so that we consume it accordingly inside the block (without affecting timings).
If we go into this path, GitalyClient.streaming_call could be removed and GitalyClient.call remains as the SSoT.
My concern with GitalyClient.streaming_call is that devs will need to think about which method to use, which is error prone if we don't raise any errors indicating what should be used.