Change component for optimization guide components in owners file

Change-Id: Ibc0ab6ef374575db330dd52e102c8c1f02176dbf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1724280
Auto-Submit: Sophie Chang <sophiechang@chromium.org>
Reviewed-by: Doug Arnett <dougarnett@chromium.org>
Commit-Queue: Sophie Chang <sophiechang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682060}

chrome/browser/optimization_guide/OWNERS

 file://components/optimization_guide/OWNERS
 
-# COMPONENT: Blink>Previews
+# COMPONENT: Internals>OptimizationGuide

components/optimization_guide/OWNERS

 file://components/previews/OWNERS
 
-# COMPONENT: Blink>Previews
+# COMPONENT: Internals>OptimizationGuide