TelemetrySavedObjectsClient: Extend createPointInTimeFinder to request all namespaces by default

[afharo]

Summary

Testing elastic#99031 with the TelemetrySavedObjectsClient also providing namespaces: ['*'] by default.

If we agree that this solves the issue found in https://github.com/elastic/kibana/pull/99031/files#r625048399 I'm happy to close this PR and create these changes on their own against master, then we can rebase the original PR 🙂

Checklist

Delete any items that are not applicable to this PR.

• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
• Unit or functional tests 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)
• Any UI touched in this PR does not create any new axe failures (run axe in browser: FF, Chrome)
• If a plugin configuration key changed, check if it needs to be allowlisted in the cloud and added to the docker list
• This renders correctly on smaller devices using a responsive layout. (You can test this in your browser)
• This was checked for cross-browser compatibility

For maintainers

• This was checked for breaking API changes and was labeled appropriately

[afharo]

cc/ @lukeelmers

[afharo]

This PR doesn't really fix the issue. Closing it. Sorry for the noise