[NFCI][metadata][LibCallsShrinkWrap] Use create{Unlikely,Likely}BranchWeights (#89465)

It does not look like 2000 is needed here in particular.

Follow up to #89464

Author: vitalybuka

llvm/lib/Transforms/Utils/LibCallsShrinkWrap.cpp

@@ -467,7 +467,7 @@ Value *LibCallsShrinkWrap::generateCondForPow(CallInst *CI,
 void LibCallsShrinkWrap::shrinkWrapCI(CallInst *CI, Value *Cond) {
   assert(Cond != nullptr && "ShrinkWrapCI is not expecting an empty call inst");
   MDNode *BranchWeights =
-      MDBuilder(CI->getContext()).createBranchWeights(1, 2000);
+      MDBuilder(CI->getContext()).createUnlikelyBranchWeights();
 
   Instruction *NewInst =
       SplitBlockAndInsertIfThen(Cond, CI, false, BranchWeights, &DTU);

llvm/test/Transforms/Util/libcalls-shrinkwrap-double.ll

@@ -448,4 +448,4 @@ define void @test_pow_strictfp(i32 %int_val, double %exp) strictfp {
 
 declare double @pow(double, double)
 
-; CHECK: ![[BRANCH_WEIGHT]] = !{!"branch_weights", i32 1, i32 2000}
+; CHECK: ![[BRANCH_WEIGHT]] = !{!"branch_weights", i32 1, i32 1048575}

llvm/test/Transforms/Util/libcalls-shrinkwrap-float.ll

@@ -350,4 +350,4 @@ declare float @log2f(float)
 declare float @logbf(float)
 declare float @log1pf(float)
 
-; CHECK: ![[BRANCH_WEIGHT]] = !{!"branch_weights", i32 1, i32 2000}
+; CHECK: ![[BRANCH_WEIGHT]] = !{!"branch_weights", i32 1, i32 1048575}

llvm/test/Transforms/Util/libcalls-shrinkwrap-long-double.ll

@@ -351,4 +351,4 @@ declare x86_fp80 @log2l(x86_fp80)
 declare x86_fp80 @logbl(x86_fp80)
 declare x86_fp80 @log1pl(x86_fp80)
 
-; CHECK: ![[BRANCH_WEIGHT]] = !{!"branch_weights", i32 1, i32 2000}
+; CHECK: ![[BRANCH_WEIGHT]] = !{!"branch_weights", i32 1, i32 1048575}