Cts fix level creation infint loop

[arthurjolo]

Summary

This PR prevents an infinite loop during the CTS level creation. It is possible that 2 sinks always cluster together during level creation and the maxHPWL never drops below maxWl, creating an infinite loop.

Type of Change

• Bug fix

Impact

Add a check if the maxHPWL drops after creating a level. If it doesn't, it means that creating more levels will never meet the conditions maxHPWL < maxWl, and it stops creating levels.

Verification

• I have verified that the local build succeeds (./etc/Build.sh).
• I have run the relevant tests and they pass.
• My code follows the repository's formatting guidelines.

• I have included tests to prevent regressions.
• I have signed my commits (DCO).

Related Issues

[Link issues here]

[gemini-code-assist]

Code Review

This pull request introduces a stop criterion in the H-Tree builder loop within HTreeBuilder.cpp. Specifically, it tracks the previous maximum half-perimeter wire length (HPWL) and terminates the loop early if the current HPWL does not improve. Additionally, a new integration test max_wl_two_sinks is added to verify this behavior and prevent regressions where the loop would otherwise run to maximum depth. There are no review comments, and I have no feedback to provide.