VisitIfStmt: Prune a redundant condition.

`S->isConsteval()` is evaluated at the top of this method.
Likely mis-merging in #75425

Author: chapuni

clang/lib/CodeGen/CoverageMappingGen.cpp

@@ -2066,7 +2066,7 @@ struct CounterCoverageMappingBuilder
       GapRegionCounter = OutCount;
     }
 
-    if (!S->isConsteval() && !llvm::EnableSingleByteCoverage)
+    if (!llvm::EnableSingleByteCoverage)
       // Create Branch Region around condition.
       createBranchRegion(S->getCond(), ThenCount,
                          subtractCounters(ParentCount, ThenCount));