[target allocator] Pprof endpoint does not correctly handle all profile types

[matej-g]

Recently, we added pprof endpoints in #1408, but it seems we are not handling all types of profiles.

For example, trying to obtain the heap profile (``) leads to 404 I response. I believe this is due to quirk in how pprof HTTP handles paths (some are under `Index` handler, others have their own handler) and how `gin` routes - we're only handling the actual index (`/`) but not other paths that belong under index handler (e.g. `/debug/pprof/heap`).