fix(ci): restore the golden header path the drift check expects

`v2-golden-drift` regenerates plane/api/v2/_generated/constants.py and requires
it byte-identical, and the generator records its source path in the file header
-- so the committed spelling must match the one CI passes, which the workflow
spells `../plane-ee/apps/api/plane/api_v2/core/schema/openapi`.

The header here read `../plane-ee-preview/...`, recorded when the golden was
regenerated from a preview checkout to pick up operations the stale one lacked.
That would have failed the drift check the moment PLANE_EE_CHECKOUT_TOKEN was
configured. The job is skipped without the token, so CI was green and would have
stayed green right up until the token existed.

Regenerated against the same preview content with the path spelled as CI spells
it: the header is the only line that differs, all 407 operations are identical,
and the file is unchanged under the black version requirements.txt now pins.

Found while investigating a Node CI failure; the Node SDK carried the identical
bug for the same reason.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014QwQ1tqb3831E7rezg5zqs

Author: Prashant-Surya

plane/api/v2/_generated/constants.py

@@ -1,5 +1,5 @@
 """Generated from the api_v2 OpenAPI golden (version 2.0.0) -- never hand-edited.
-Source: ../plane-ee-preview/apps/api/plane/api_v2/core/schema/openapi
+Source: ../plane-ee/apps/api/plane/api_v2/core/schema/openapi
 Regenerate: python scripts/generate_v2_constants.py <path-to>/api_v2/core/schema/openapi"""
 
 from collections.abc import Sequence