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).