feat(collector): optimize telemetryapireceiver trace and span id generation

[wpessers]

Use crypto/rand's Read method directly. Instead of reinitializing and seeding the rng on each span / trace id generation. Saving:

1. Heap allocations
   • rand.NewSource(rngSeed)
   • rand.New(...)
2. Some init logic - CPU time
   • rand.NewSource(rngSeed) - PRNG state initialization (also apparently not safe for concurrent use)
3. Probably negligible but function call overhead of calling rand.NewSource(rngSeed) and rand.New(...)

What remains now is basically a very efficient syscall, with no heap allocations.

[wpessers]

Noticed this in the existing code when reviewing changes from #2058

[herin049]

LGTM