[uiSettings] Extend toast lifetime (elastic#169899)

## Summary

- Extend toast lifetime to `15s`.
- Resolves elastic#135950 

### Checklist

Delete any items that are not applicable to this PR.

- [ ] Any text added follows [EUI's writing
guidelines](https://elastic.github.io/eui/#/guidelines/writing), uses
sentence case text and includes [i18n
support](https://github.com/elastic/kibana/blob/main/packages/kbn-i18n/README.md)
- [ ]
[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
was added for features that require explanation or tutorials
- [ ] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios
- [ ] Any UI touched in this PR is usable by keyboard only (learn more
about [keyboard accessibility](https://webaim.org/techniques/keyboard/))
- [ ] Any UI touched in this PR does not create any new axe failures
(run axe in browser:
[FF](https://addons.mozilla.org/en-US/firefox/addon/axe-devtools/),
[Chrome](https://chrome.google.com/webstore/detail/axe-web-accessibility-tes/lhdoppojpmngadmnindnejefpokejbdd?hl=en-US))
- [ ] If a plugin configuration key changed, check if it needs to be
allowlisted in the cloud and added to the [docker
list](https://github.com/elastic/kibana/blob/main/src/dev/build/tasks/os_packages/docker_generator/resources/base/bin/kibana-docker)
- [ ] This renders correctly on smaller devices using a responsive
layout. (You can test this [in your
browser](https://www.browserstack.com/guide/responsive-testing-on-local-server))
- [ ] This was checked for [cross-browser
compatibility](https://www.elastic.co/support/matrix#matrix_browsers)


### For maintainers

- [ ] This was checked for breaking API changes and was [labeled
appropriately](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

Signed-off-by: Willie Hung <[email protected]>
Co-authored-by: Kibana Machine <[email protected]>

src/plugins/advanced_settings/public/management_app/components/form/form.tsx

@@ -191,6 +191,7 @@ export class Form extends PureComponent<FormProps> {
       title: i18n.translate('advancedSettings.form.requiresPageReloadToastDescription', {
         defaultMessage: 'One or more settings require you to reload the page to take effect.',
       }),
+      toastLifeTimeMs: 15000,
       text: toMountPoint(
         <KibanaThemeProvider theme$={this.props.theme}>
           <EuiFlexGroup justifyContent="flexEnd" gutterSize="s">