Use unique handle for discovery and generic targets to save GC and memory

[mattdurham]

Request

Targets/Discovery are represented as list(map[string]), with discovery running every 5 seconds in very large clusters the garbage collector can spike due to creating these labels. The names especially are repeated. The hard part is implementing the capsule value so hard coded targets still work. This is because in the alloy runtime there is a bug where you cannot convert from list/map to a capsule value.

In reviewing profiles this code was by far the largest allocator.

alloy/internal/component/discovery/discovery.go

Line 212 in 5845b2c

allTargets := []Target{}

Use case

Reduce memory and cpu