chore: stabilize VCR cassette output to reduce regeneration noise

Add X-GDC-CANCEL-TOKEN to NON_STATIC_HEADERS so its random UUID
values are replaced with PLACEHOLDER, matching DATE and X-GDC-TRACE-ID.

Switch yaml.dump sort_keys from False to True so all dictionary keys
(including request/response bodies) are serialized in deterministic
alphabetical order, eliminating key reordering diffs on regeneration.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
risk: low

Author: jaceksan

packages/tests-support/src/tests_support/vcrpy_utils.py

@@ -12,7 +12,7 @@
 from vcr.record_mode import RecordMode
 
 VCR_MATCH_ON = ("method", "scheme", "host", "port", "path", "query", "body")
-NON_STATIC_HEADERS = ["DATE", "X-GDC-TRACE-ID"]
+NON_STATIC_HEADERS = ["DATE", "X-GDC-CANCEL-TOKEN", "X-GDC-TRACE-ID"]
 HEADERS_STR = "headers"
 PLACEHOLDER = ["PLACEHOLDER"]
 
@@ -76,7 +76,7 @@ def serialize(self, cassette_dict: dict[str, Any]) -> str:
                 except (JSONDecodeError, UnicodeDecodeError):
                     # these exceptions are expected while getting file content
                     continue
-        return yaml.dump(cassette_dict, Dumper=IndentDumper, sort_keys=False)
+        return yaml.dump(cassette_dict, Dumper=IndentDumper, sort_keys=True)
 
 
 def custom_before_request(request, headers_str: str = HEADERS_STR):