chore: fix eslint wasn't running in test dir (#11036)

This PR fixes 2 eslint config issues that prevented it from running in our test dir

- spec files were ignored by the root eslint config. This should have only ignored spec files within our packages, as they are ignored by the respective package tsconfigs
- defining the payload plugin crashed eslint in our test dir, as it was already defined in the root eslint config it was inheriting

test/eslint.config.js

@@ -17,9 +17,6 @@ export const testEslintConfig = [
         tsconfigRootDir: import.meta.dirname,
       },
     },
-    plugins: {
-      payload: payloadPlugin,
-    },
     rules: {
       'payload/no-relative-monorepo-imports': 'error',
     },