Remove underscore from "all_threads" track (#3210)
Remove underscore from "all_threads" track (#3210)

This is a regression from e682957f4d1d05f52c9cef88beea4623b6342e04 from October
2020. Either way, the underscore shouldn't be there. The "Sampling", "Top-Down"
and "Bottom-Up" view also don't have the underscore.

Test: Take a capture.
google/orbit,google/orbit,google/orbit,google/orbit