…ch (#31933)"

This reverts commit 3a94e50.

…ch" (#32415)

Reverts #31933

…data batch (#32417)

Original attempt was #31933, reverted
in #32415.

…#31933)

Currently, the peer name is returned with the completion of the
send_initial_metadata op, which does not make sense, because with
retries, we don't actually know the peer name until we complete the
recv_initial_metadata op. This PR changes our code to return the peer
string as an attribute of the recv_initial_metadata op, so that it is
not available to the application until that point. This change may be
user-visible, but since our API docs don't seem to guarantee exactly
when this data will be available, it's not technically a breaking
change.

Note that in the promise-based stack, we were already assuming that the
peer string would be returned as part of the recv_initial_metadata
batch, so this PR helps reduce risk for the promise conversion by making
this semantic change now, thus decoupling it from the promise
conversion.

I have also changed the representation of the string in the metadata
batch to be a `grpc_core::Slice` instead of a `std::string`, so that we
can just take a ref to the string held in the transport instead of
having to copy the whole string for every call.

…ch" (grpc#32415)

Reverts grpc#31933

…data batch (grpc#32417)

Original attempt was grpc#31933, reverted
in grpc#32415.

Currently, the peer name is returned with the completion of the
send_initial_metadata op, which does not make sense, because with
retries, we don't actually know the peer name until we complete the
recv_initial_metadata op. This PR changes our code to return the peer
string as an attribute of the recv_initial_metadata op, so that it is
not available to the application until that point. This change may be
user-visible, but since our API docs don't seem to guarantee exactly
when this data will be available, it's not technically a breaking
change.

Note that in the promise-based stack, we were already assuming that the
peer string would be returned as part of the recv_initial_metadata
batch, so this PR helps reduce risk for the promise conversion by making
this semantic change now, thus decoupling it from the promise
conversion.

I have also changed the representation of the string in the metadata
batch to be a `grpc_core::Slice` instead of a `std::string`, so that we
can just take a ref to the string held in the transport instead of
having to copy the whole string for every call.

…ch" (#32415)

Reverts #31933

…data batch (#32417)

Original attempt was #31933, reverted
in #32415.