cloud_proxy: handle stream disconnects gracefully (#14685)

Previously we were printing out bad errors for expected cases like
clients disconnecting. Now we only debug log when that happens (which
still might help in cases where we're figuring out why an integration
isn't working). For other errors, we print out a proper warning now

server/cloud_proxy.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"log/slog"
@@ -204,7 +205,25 @@ func proxyCloudRequestWithPath(c *gin.Context, body []byte, path string, disable
 	c.Status(resp.StatusCode)
 
 	if err := copyProxyResponseBody(c.Writer, resp.Body); err != nil {
-		c.Error(err) //nolint:errcheck
+		ctxErr := c.Request.Context().Err()
+		if errors.Is(err, context.Canceled) && errors.Is(ctxErr, context.Canceled) {
+			slog.Debug(
+				"cloud proxy response stream closed by client",
+				"path", c.Request.URL.Path,
+				"status", resp.StatusCode,
+			)
+			return
+		}
+
+		slog.Warn(
+			"cloud proxy response copy failed",
+			"path", c.Request.URL.Path,
+			"status", resp.StatusCode,
+			"request_context_canceled", ctxErr != nil,
+			"request_context_err", ctxErr,
+			"error", err,
+		)
+		return
 	}
 }