fix(ci): repair direct-backport-push YAML and post backport result comments

.github/scripts/compose-backport-message.py

@@ -0,0 +1,56 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Composes the backport commit message: insert "(backported from commit X)"
+# between the message body and the trailer block (the trailing run of
+# `Key: value` lines such as Co-Authored-By and Signed-off-by) so trailers
+# stay contiguous at the bottom — that's where git itself parses them.
+#
+# The trailer block, by git convention, is the run of `Key: value` lines
+# after the LAST blank line in the message, and only counts if EVERY line
+# after that blank line is in trailer format. This avoids mis-detecting a
+# Conventional Commits subject like "feat: foo" or a body line like
+# "References:" as a trailer.
+#
+# Usage: original-message-on-stdin | compose-backport-message.py <merge-sha>
+
+import re
+import sys
+
+sha = sys.argv[1]
+msg = sys.stdin.read().rstrip("\n")
+lines = msg.split("\n")
+trailer_re = re.compile(r"^[A-Za-z][A-Za-z0-9-]*:\s")
+
+last_blank = -1
+for idx in range(len(lines) - 1, -1, -1):
+    if lines[idx] == "":
+        last_blank = idx
+        break
+
+trailer_start = len(lines)
+if last_blank != -1:
+    candidate = lines[last_blank + 1 :]
+    if candidate and all(trailer_re.match(line) for line in candidate):
+        trailer_start = last_blank + 1
+
+backport = f"(backported from commit {sha})"
+if trailer_start == len(lines):
+    print(msg + "\n\n" + backport)
+else:
+    body = "\n".join(lines[:trailer_start]).rstrip("\n")
+    trailers = "\n".join(lines[trailer_start:])
+    print(body + "\n\n" + backport + "\n\n" + trailers)