[dependabot.yml] Remove "eng/tools" to fix root updates (Azure#35913)

Author: mikeharder

.github/dependabot.yml

@@ -1,9 +1,13 @@
 version: 2
 updates:
+  # For monorepos, only the root folder should be listed (not the sub-folders).
+  # We may also need to set "versioning-strategy" to "increase" rather than "increase-if-necessary",
+  # to update both package.json and package-lock.json files.  In our case, we don't really care
+  # if the package.json files are updated or not, just that package-lock.json is update.
+  # https://github.com/dependabot/dependabot-core/issues/4993#issuecomment-1289133027
   - package-ecosystem: "npm"
     directories:
       - "/"
-      - "/eng/tools/**"
     schedule:
       interval: "daily"
     ignore: