Refactor CONTRACT_ID injection logic to only occur in LSP mode

[JoshuaBatty]

Description

This PR modifies CONTRACT_ID injection to only occur in LSP mode, preventing unnecessary dummy values from being added when check() is called outside LSP contexts. Fixes issues with IR test suite where core was incorrectly receiving a CONTRACT_ID definition.

Checklist

• I have linked to any relevant issues.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation where relevant (API docs, the reference, and the Sway book).
  • If my change requires substantial documentation changes, I have requested support from the DevRel team
• I have added tests that prove my fix is effective or that my feature works.
• I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• I have requested a review from the relevant team or maintainers.

[codspeed-hq]

CodSpeed Performance Report

Merging #7001 will not alter performance

_{Comparing josh/dummy_contract_id (781ede9) with master (13542d2)}

Summary

✅ 22 untouched benchmarks

[jjcnn]

Solves the problem I was having. Thanks.