Apply stderr-capture sleep to Rust/Go/Python/.NET e2e tests

The shared snapshot should_capture_stderr_output.yaml was re-recorded with
'sleep 0.5' to make stdout/stderr interleave deterministic. Update the
remaining SDK e2e tests that exercise this snapshot to send the matching
command. Java has no equivalent test.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: SteveSandersonMS

dotnet/test/E2E/BuiltinToolsE2ETests.cs

@@ -49,7 +49,7 @@ public async Task Should_Capture_Stderr_Output()
         var session = await CreateSessionAsync();
         var msg = await session.SendAndWaitAsync(new MessageOptions
         {
-            Prompt = "Run 'echo error_msg >&2; echo ok' and tell me what stderr said. Reply with just the stderr content.",
+            Prompt = "Run 'echo error_msg >&2; sleep 0.5; echo ok' and tell me what stderr said. Reply with just the stderr content.",
         }, SendTimeout);
         Assert.Contains("error_msg", msg?.Data.Content ?? string.Empty);
     }

go/internal/e2e/builtin_tools_e2e_test.go

@@ -68,7 +68,7 @@ func TestBuiltinToolsE2E(t *testing.T) {
 		sendCtx, cancel := context.WithTimeout(t.Context(), sendTimeout)
 		defer cancel()
 		msg, err := session.SendAndWait(sendCtx, copilot.MessageOptions{
-			Prompt: "Run 'echo error_msg >&2; echo ok' and tell me what stderr said. Reply with just the stderr content.",
+			Prompt: "Run 'echo error_msg >&2; sleep 0.5; echo ok' and tell me what stderr said. Reply with just the stderr content.",
 		})
 		if err != nil {
 			t.Fatalf("SendAndWait failed: %v", err)

python/e2e/test_builtin_tools_e2e.py

@@ -47,7 +47,7 @@ async def test_should_capture_stderr_output(self, ctx: E2ETestContext):
         )
         try:
             message = await session.send_and_wait(
-                "Run 'echo error_msg >&2; echo ok' and tell me what stderr said. "
+                "Run 'echo error_msg >&2; sleep 0.5; echo ok' and tell me what stderr said. "
                 "Reply with just the stderr content.",
                 timeout=SEND_TIMEOUT,
             )

rust/tests/e2e/builtin_tools.rs

@@ -62,7 +62,7 @@ async fn should_capture_stderr_output() {
                 .expect("create session");
 
             let msg = session
-                .send_and_wait(message("Run 'echo error_msg >&2; echo ok' and tell me what stderr said. Reply with just the stderr content."))
+                .send_and_wait(message("Run 'echo error_msg >&2; sleep 0.5; echo ok' and tell me what stderr said. Reply with just the stderr content."))
                 .await
                 .expect("send")
                 .expect("assistant message");