…+ right schemars output (#22920)

With #22907 I want to start outputting the schema for rule configs.
Boths rules (`jest/no-restricted-jest-methods` & `vitest/no-restricted-vi-methods`) had not the right user configuration output:

Upstream docs:
- https://github.com/vitest-dev/eslint-plugin-vitest/blob/main/docs/rules/no-restricted-vi-methods.md
- https://github.com/jest-community/eslint-plugin-jest/blob/main/docs/rules/no-restricted-jest-methods.md

The Schema before this PR:

```ts
  "jest/no-restricted-jest-methods"?:
    | [AllowWarnDeny]
    | [
        AllowWarnDeny,
        {
          /**
           * A mapping of restricted Jest method names to custom messages - or
           * `null`, for a generic message.
           */
          restrictedJestMethods?: {
            [k: string]: string;
          };
          [k: string]: unknown;
        }
      ];
```

With this PR:
```ts
  "jest/no-restricted-jest-methods"?:
    | [AllowWarnDeny]
    | [
        AllowWarnDeny,
        {
          [k: string]: string | null;
        }
      ];
```

---

Bonus: used `Option<CompactStr>` for more performance (?)