FlameGraph: display short function name when a flamegraph node size is small

### Feature description When a user query a go program, most of the time it only sees package names all over the flamegraph on each node. If a user aligns to the right, then it displays the last letters of functions which are also hard to read from the middle. In order to navigate, users need to either zoom or hover on nodes. <img width="1455" height="888" alt="Image" src="https://github.com/user-attachments/assets/c72fafb1-edb9-4a76-bad0-db2c89501ec7" /> We should consider exposing a third option of displaying a function name without a package if there is no enough room to include package. Here's how it's done in `pprof` <img width="1852" height="833" alt="Image" src="https://github.com/user-attachments/assets/71151c1e-c0b4-4916-af1e-28920476be0d" /> Slightly relevant issue: https://github.com/grafana/profiles-drilldown/issues/420 **Is your feature request related to a problem? Please describe.** <!-- A clear and concise description of what the problem is. Ex. I'm always frustrated when [...] --> **Describe the solution you'd like** <!-- A clear and concise description of what you want to happen. --> <!-- Add screenshots about the feature request here. --> ### Alternatives considered **Describe alternatives you've considered** <!-- A clear and concise description of any alternative solutions or features you've considered. --> ### Additional context <!-- Add any other context about the feature request here. -->