[devicelab] Remove and stop recording unused sub_result metrics. #143532
Description
The devicelab allows tests to provide custom dimensions, and a number of them have either never regressed, never stabilized, or aren't useful in a post Skia world.
- Unused
120hz_frame_percentage
30hz_frame_percentage
60hz_frame_percentage
80hz_frame_percentage
90hz_frame_percentage
- Skia Specific
layer_cache_count
layer_cache_memory
picture_cache_count
picture_cache_memory