The SampleGraph should use the full thread to compute its samples

Currently the SampleGraph uses the filtered thread only. This leads to some issues, especially when using the inverted tree, because the category isn't properly computed in this case.

Instead we should use the full thread to compute this information. This would also make it possible to show the filtered out samples with a different color (currently they're not displayed at all).

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-593)