Remove redundant rule configuration

The `@gitlab/vue-prefer-dollar-scopedslots` rule was enabled by default
in `@gitlab/eslint-plugin@15.0.0` (see the [changelog][1]), and we
already depend on 16.0.0, so this can be removed.

Part of
https://gitlab.com/gitlab-org/frontend/eslint-plugin/-/issues/54.

[1]: https://gitlab.com/gitlab-org/frontend/eslint-plugin/-/blob/main/CHANGELOG.md#1500-2022-07-29

.eslintrc.yml

@@ -53,7 +53,6 @@ rules:
       - '^$'
       - '^variables$'
       - 'attrs?$'
-  '@gitlab/vue-prefer-dollar-scopedslots': error
   no-param-reassign:
     - error
     - props: true