Update CODEOWNERS with vbarr in benchmarking folder

For two goals

1. Help with changes in max xpk runner and related workflows 
2. Work on a customer facing test MaxTest in that directory and needs help getting approvals and I am familiar with that work

Author: Obliviour

.github/CODEOWNERS

@@ -33,4 +33,4 @@ src/MaxText/inference_mlperf @vipannalla @mitalisi @gpolovets1 @mailvijayasingh
 .github/workflows @gobbleturk @khatwanimohit @shralex @parambole @bvandermoon @richjames0
 
 # Benchmarking/Recipes
-benchmarks @SujeethJinesh @bvandermoon @richjames0 @shralex @vipannalla @mitalisi @RissyRan @shauryagup @NuojCheng @gobbleturk @khatwanimohit
+benchmarks @SujeethJinesh @bvandermoon @richjames0 @shralex @vipannalla @mitalisi @RissyRan @shauryagup @NuojCheng @gobbleturk @khatwanimohit @Obliviour