Fix: Expression route handling fix for Konnect and < v3.7.0

[Prashansa-K]

Summary

v3.7.0 added changes to allow traditional route fields with expression routes, thus making expression router a superset of traditional router. Ref: https://github.com/Kong/kong/pull/12667 Thus, keys like regex_priority are not supported in versions lesser than 3.7.0.

Added a gating logic in state builder for the necessary changes and fixed tests. Fix #1250

Full changelog

• Added gating logic in state builder
• Fixed tests for the same

Issues resolved

Fix #1250

Documentation

• [ ] Link to the website documentation PR

Testing

• [x] Unit tests
• [ ] E2E tests
• [ ] Manual testing on Universal
• [ ] Manual testing on Kubernetes
• [x] Manual testing using deck with gateway versions 3.6.1.7 and 3.7.1.2

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 41.35%. Comparing base (e7e4f68) to head (3f999c9).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #118 +/- ## ========================================== + Coverage 41.23% 41.35% +0.12% ========================================== Files 75 75 Lines 10892 10895 +3 ========================================== + Hits 4491 4506 +15 + Misses 5937 5925 -12 Partials 464 464 ```

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