Revert "Merge pull request #3078 from bnbarham/update-codeowners"

This reverts commit 18628b2, reversing
changes made to eda5e2f. Code owners
are the branch managers on the release branch.

Author: bnbarham

.github/CODEOWNERS

@@ -8,7 +8,7 @@
 # Order is important. The last matching pattern has the most precedence.
 
 # Owner of anything in SwiftSyntax not owned by anyone else.
-* @ahoppen @bnbarham @hamishknight @rintaro
+* @ahoppen @bnbarham
 
 # Macros
 /Sources/SwiftSyntaxMacros @DougGregor