Revert "[http2] Stabilize rst_stream experiment"

This reverts commit aef71dc.

Author: yashykt

bazel/experiments.bzl

@@ -2439,7 +2439,8 @@ void grpc_chttp2_cancel_stream(grpc_chttp2_transport* t, grpc_chttp2_stream* s,
             // sent headers yet (still in "idle" state). Note that since we have
             // marked the stream closed above, we won't be writing to it
             // anymore.
-            if (t->is_client && !sent_initial_metadata) {
+            if (grpc_core::IsRstStreamFixEnabled() && t->is_client &&
+                !sent_initial_metadata) {
               return;
             }
             grpc_chttp2_add_rst_stream_to_next_write(

src/core/ext/transport/chttp2/transport/chttp2_transport.cc

@@ -222,6 +222,11 @@
   expiry: 2025/06/06
   owner: [email protected]
   test_tags: []
+- name: rst_stream_fix
+  description: Fix for RST_STREAM - do not send for idle streams (https://github.com/grpc/grpc/issues/38758)
+  expiry: 2025/06/06
+  owner: [email protected]
+  test_tags: []
 - name: schedule_cancellation_over_write
   description: Allow cancellation op to be scheduled over a write
   expiry: 2025/10/01

src/core/lib/experiments/experiments.cc

@@ -82,6 +82,8 @@
   default: false
 - name: promise_based_http2_server_transport
   default: false
+- name: rst_stream_fix
+  default: true
 - name: schedule_cancellation_over_write
   default: false
 - name: server_global_callbacks_ownership