chore: use mobx-react (#4884)

use mobx-react to fix IRM build

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## Checklist

- [ ] Unit, integration, and e2e (if applicable) tests updated
- [x] Documentation added (or `pr:no public docs` PR label added if not
required)
- [x] Added the relevant release notes label (see labels prefixed w/
`release:`). These labels dictate how your PR will
    show up in the autogenerated release notes.

grafana-plugin/src/containers/PluginConfigPage/PluginConfigPage.tsx

@@ -3,7 +3,7 @@ import React, { useEffect, useState } from 'react';
 import { css } from '@emotion/css';
 import { GrafanaTheme2, PluginConfigPageProps, PluginMeta } from '@grafana/data';
 import { Alert, Field, HorizontalGroup, Input, LoadingPlaceholder, useStyles2, VerticalGroup } from '@grafana/ui';
-import { observer } from 'mobx-react-lite';
+import { observer } from 'mobx-react';
 import { Controller, useForm } from 'react-hook-form';
 import { useNavigate } from 'react-router-dom-v5-compat';
 import { OnCallPluginMetaJSONData } from 'types';