[NFC][MLGO] Fix vector sizing

The bots only build release mode, and the use of `reserve` instead of
`resize`, while not causing invalid memory accesses, is incorrect.

Author: mtrofin

llvm/lib/Analysis/ReleaseModeModelRunner.cpp

@@ -52,7 +52,7 @@ ReleaseModeModelRunner::ReleaseModeModelRunner(LLVMContext &Ctx)
       CompiledModel(std::make_unique<llvm::InlinerSizeModel>()) {
   assert(CompiledModel && "The CompiledModel should be valid");
 
-  FeatureIndices.reserve(NumberOfFeatures);
+  FeatureIndices.resize(NumberOfFeatures);
 
   for (size_t I = 0; I < NumberOfFeatures; ++I) {
     const int Index =