chore: remove miraleung from CODEOWNERS (#891)

Author: meltsufin

gapic-generator-java/.github/CODEOWNERS

@@ -4,4 +4,4 @@
 # For syntax help see:
 # https://help.github.com/en/github/creating-cloning-and-archiving-repositories/about-code-owners#codeowners-syntax
 
-*     @miraleung @googleapis/actools-java @googleapis/cloud-java-team-teamsync
+*     @googleapis/actools-java @googleapis/cloud-java-team-teamsync