Disable parent-entity-call feature in schema stitching

[DanielFang71]

Disable parent-entity-call feature in schema stitching

Summary

This PR disables the parent-entity-call feature introduced in recent versions PR 6117 of the schema stitching library. This change is necessary to maintain backwards compatibility with our existing implementation while we work on a long-term solution to address underlying schema design issues.

Changes

• Disabled the parent-entity-call feature in the gateway
• Skipped parent-entity-call test suite until audit repo changes are merged
  • Updated related tests to expect null values for unresolved fields

Motivation

Recent updates to the schema stitching library (PRs #6117 and #6092) introduced changes in how the query planner resolves fields across multiple subschemas. While these changes fix a bug, within our enterprise usecase, they create unexpected additional traffic to our subschemas and break existing functionality in our implementation.

Enterprise Impact

As one of the large enterprise users of this library, we have built significant business-critical functionality based on the previous behavior. While we acknowledge we're depending on what was technically a bug in the previous version:

1. The current implementation is deeply integrated into our production systems
2. An immediate migration to the new behavior would require significant coordination across multiple teams and services
3. The additional cross-schema resolution attempts would create substantial unnecessary load on our production systems

Short-term Solution

This PR provides a temporary solution and demonstrates a way to switch off this feature and revert to the previous behavior, so that we could introduce a new config to turn it off, allowing us to:

• Maintain system stability
• Prevent unexpected production issues
• Give us time to properly plan and execute the migration

Long-term Plan

We are committed to:

1. Conducting a comprehensive schema quality audit
2. Developing a proper schema design that aligns with the intended behavior
3. Creating a controlled migration path that doesn't disrupt business operations
4. Working with the community to implement these changes in a sustainable way

Testing

All test cases have passed successfully, except for the intentionally skipped parent-entity-call tests.

Reviewers

@DenisBadurina

Please review to ensure there are no unintended side effects on other features.