[NFC][CODEOWNERS] Update codeowners (#6022)

* Reassign top level uncovered items to myself
* Rely on group codeowners for clang-offload-*

Author: Pavel Chupin

.github/CODEOWNERS

@@ -1,4 +1,4 @@
-* @bader
+* @pvchupin
 
 # Front-end compiler
 clang/ @intel/dpcpp-cfe-reviewers
@@ -48,7 +48,7 @@ xptifw/ @intel/llvm-reviewers-runtime
 llvm/ @intel/dpcpp-tools-reviewers
 
 # Clang offload tools
-clang/tools/clang-offload-*/ @sndmitriev @intel/dpcpp-tools-reviewers
+clang/tools/clang-offload-*/ @intel/dpcpp-tools-reviewers
 
 # Explicit SIMD
 ESIMD/ @intel/dpcpp-esimd-reviewers