CLOUDP-327328: Replace dependabot reviewers with codeowners (#788)

Author: lovisaberggren

.github/CODEOWNERS

@@ -1,2 +1,4 @@
 # Maintained by the APIx team
-*       @mongodb/apix
+*                         @mongodb/apix
+/tools/cli/               @mongodb/apix-2
+/tools/spectral/ipa/      @mongodb/apix1

.github/dependabot.yml

@@ -8,23 +8,17 @@ updates:
     open-pull-requests-limit: 20
     commit-message:
       prefix: "chore"
-    reviewers:
-      - "mongodb/apix-2"
   - package-ecosystem: github-actions
     directory: "/"
     schedule:
       interval: weekly
       day: tuesday
     commit-message:
       prefix: "chore"
-    reviewers:
-      - "mongodb/apix-2"
   - package-ecosystem: npm
     directory: "/"
     schedule:
       interval: weekly
       day: tuesday
     commit-message:
       prefix: "chore"
-    reviewers:
-      - "mongodb/APIx"