Optimize Go object allocation

[grcevski]

I made a few changes to reduce the amount of transient memory we allocate. With this change, the majority of allocations are out of our control. Very little is in the ring buffer path, the rest are all about working with the SDKs to generate metrics and traces.

pprof after the changes

profile (1).pb.gz

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 87.14286% with 9 lines in your changes missing coverage. Please review.

Project coverage is 81.69%. Comparing base (27dc018) to head (3f559a9).

Files	Patch %	Lines
pkg/internal/infraolly/process/snapshot.go	0.00%	5 Missing and 1 partial :warning:
pkg/internal/export/alloy/traces.go	0.00%	0 Missing and 1 partial :warning:
pkg/internal/export/otel/metrics.go	0.00%	0 Missing and 1 partial :warning:
pkg/internal/export/prom/prom.go	80.00%	0 Missing and 1 partial :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1028      +/-   ##
==========================================
+ Coverage   81.68%   81.69%   +0.01%     
==========================================
  Files         137      137              
  Lines       10923    10948      +25     
==========================================
+ Hits         8922     8944      +22     
- Misses       1494     1497       +3     
  Partials      507      507              

Flag	Coverage Δ
integration-test	56.28% <67.14%> (-0.10%)	:arrow_down:
k8s-integration-test	59.10% <54.28%> (+0.03%)	:arrow_up:
oats-test	37.36% <50.00%> (+0.02%)	:arrow_up:
unittests	51.09% <45.71%> (+0.07%)	:arrow_up:

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