perf(get): include small objects in codec streaming (#6004)

Co-authored-by: heihutu <heihutu@gmail.com>

crates/e2e_test/src/get_codec_streaming_compat_test.rs

@@ -189,8 +189,6 @@ mod tests {
             ("RUSTFS_GET_CODEC_STREAMING_ROLLOUT_PCT", "100"),
             ("RUSTFS_GET_CODEC_STREAMING_BODY_COMPAT_CONFIRMED", "true"),
             ("RUSTFS_GET_CODEC_STREAMING_HEADER_COMPAT_CONFIRMED", "true"),
-            // Lower the min-size floor so every non-inline object below is eligible.
-            ("RUSTFS_GET_CODEC_STREAMING_MIN_SIZE", "4096"),
             // Route multipart objects through per-part codec streaming too.
             ("RUSTFS_GET_CODEC_STREAMING_MULTIPART_ENABLE", "true"),
             // Lock optimization is on by default, but pin it so the gate's
@@ -315,6 +313,13 @@ mod tests {
                 },
                 payload(64 * 1024, 2),
             ),
+            (
+                Shape {
+                    key: "small-non-inline-256kib-plus",
+                    expect_large: true,
+                },
+                payload(256 * 1024 + 1, 6),
+            ),
             (
                 Shape {
                     key: "mid-1_5mib",