CODEOWNERS - Remove global matching (#6376)

Since some PRs are asking reviews from `treeherder-admins` when they should not.

CODEOWNERS

@@ -1,15 +1,14 @@
 # Visit https://help.github.com/en/github/creating-cloning-and-archiving-repositories/about-code-owners#codeowners-syntax
 # for learning about the syntax
 
-*                           @mozilla/treeherder-admins
 # Dot files at the root level
 /.*                         @armenzg
 /app.json                   @armenzg
 /docker-compose.yml         @armenzg
-/docker/*                   @armenzg
-management/commands/*       @armenzg
-extract/                    @klahnakoski
-push-health/*               @camd
-intermittent-failures/*     @sarah-clements
-intermittents-commenter/*   @sarah-clements
-perfherder/*                @ionutgoldan
+/docker/**                  @armenzg
+management/commands/**      @armenzg
+extract/**                  @klahnakoski
+push-health/**              @camd
+intermittent-failures/**    @sarah-clements
+intermittents-commenter/**  @sarah-clements
+perfherder/**               @ionutgoldan