Remove redundant STA calls in RepairDesign

[dsengupta0628]

Summary

Cleans up redundant STA calls in the resizer's RepairDesign, continuing the work started in #10480

Changes

• RepairDesign::performEarlySizingRound / repairDesign: drop redundant searchPreamble() + findAllArrivals(), the explicit findRequireds(drvr->level()+1), the delaysInvalid() call, and the per-net incremental-timing block (ensureLevelized/findDelays/findArrivals). These are consolidated into a single findRequired(drvr) prerequisite in performGainBuffering.
• performGainBuffering: take the driver Vertex* instead of const Pin* (avoids redundant pin→vertex lookups), and add the explicit findRequired(drvr) needed before vertexWorstSlackPath.
• Replace manual Vertex::setSlewAnnotated(false, ...) loops with the Sta::unsetAnnotatedSlew(...) API; use RiseFall::range() instead of explicit rise/fall pairs.
• RepairTargetCollector: route makeExceptionTo and findPathEnds through the Sta API instead of sdc_/search_ directly.

Note: this is the first of two steps. A follow-up will add findRequired inside Sta::vertexWorstSlackPath (the proper place for it), after which the explicit findRequireds/findRequired calls that remain in the resizer can be removed.

Type of Change

• Refactoring

Impact

None

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 signed my commits (DCO).

[gemini-code-assist]

Code Review

This pull request refactors the timing analysis and repair flow in RepairDesign and RepairTargetCollector. Key changes include updating performGainBuffering to accept a sta::Vertex* instead of a sta::Pin*, adding a prerequisite call to sta_->findRequired(drvr), and removing redundant incremental timing updates and arrival/required search calls. Additionally, manual loops for un-annotating slews are replaced with sta_->unsetAnnotatedSlew, and sdc_->makeExceptionTo and search_->findPathEnds are updated to use sta_ equivalents. There are no review comments, so I have no feedback to provide.

[dsengupta0628]

secure-ci: http://secure-ci:8080/job/SB/job/secure-test-resizer6-apply/

[maliberty]

@codex review

[maliberty]

If the CI is ok I don't have anything to add.

[dsengupta0628]

If the CI is ok I don't have anything to add.

secure CI was fine. Public CI had a small variation in GRT TNS though CF TNS was fine. I created a metric PR The-OpenROAD-Project/OpenROAD-flow-scripts#4308