[PROCS-3827] Update the process host resolution and add additional tests

[wiyu]

What does this PR do?

• Moves the non-process agent host resolution to happen to the top of the function to improve code readability
• Adds additional host resolution testing for different agent flavors

Motivation

Improve test coverage of the process host resolution

Additional Notes

Possible Drawbacks / Trade-offs

Describe how to test/QA your changes

• Unit tests cover the behavior

[pr-commenter[bot]]

Bloop Bleep... Dogbot Here

Regression Detector Results

Run ID: 52e7d864-59a3-4202-be5c-db756d2a8d4c Baseline: 627454c7d30fd69375d83b928d42e62282bdde78 Comparison: c232704ddee00256456ab2eb878a4e6d1900339b

Performance changes are noted in the perf column of each table:

• ✅ = significantly better comparison variant performance
• ❌ = significantly worse comparison variant performance
• ➖ = no significant change in performance

No significant changes in experiment optimization goals

Confidence level: 90.00% Effect size tolerance: |Δ mean %| ≥ 5.00%

There were no significant changes in experiment optimization goals at this confidence level and effect size tolerance.

Experiments ignored for regressions

Regressions in experiments with settings containing erratic: true are ignored.

perf	experiment	goal	Δ mean %	Δ mean % CI
➖	file_to_blackhole	% cpu utilization	+5.53	[-1.38, +12.44]

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI
➖	file_to_blackhole	% cpu utilization	+5.53	[-1.38, +12.44]
➖	otel_to_otel_logs	ingress throughput	+0.67	[+0.07, +1.27]
➖	process_agent_real_time_mode	memory utilization	+0.54	[+0.50, +0.58]
➖	process_agent_standard_check	memory utilization	+0.41	[+0.38, +0.44]
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	+0.25	[-1.18, +1.69]
➖	uds_dogstatsd_to_api	ingress throughput	+0.00	[-0.00, +0.00]
➖	tcp_dd_logs_filter_exclude	ingress throughput	-0.00	[-0.00, +0.00]
➖	trace_agent_json	ingress throughput	-0.00	[-0.02, +0.02]
➖	trace_agent_msgpack	ingress throughput	-0.02	[-0.03, -0.01]
➖	process_agent_standard_check_with_stats	memory utilization	-0.23	[-0.26, -0.20]
➖	idle	memory utilization	-0.36	[-0.39, -0.32]
➖	file_tree	memory utilization	-0.54	[-0.62, -0.47]
➖	tcp_syslog_to_blackhole	ingress throughput	-1.31	[-1.36, -1.25]
➖	basic_py_check	% cpu utilization	-2.41	[-4.70, -0.13]

Explanation

A regression test is an A/B test of target performance in a repeatable rig, where "performance" is measured as "comparison variant minus baseline variant" for an optimization goal (e.g., ingress throughput). Due to intrinsic variability in measuring that goal, we can only estimate its mean value for each experiment; we report uncertainty in that value as a 90.00% confidence interval denoted "Δ mean % CI".

For each experiment, we decide whether a change in performance is a "regression" -- a change worth investigating further -- if all of the following criteria are true:

1. Its estimated |Δ mean %| ≥ 5.00%, indicating the change is big enough to merit a closer look.

2. Its 90.00% confidence interval "Δ mean % CI" does not contain zero, indicating that if our statistical model is accurate, there is at least a 90.00% chance there is a difference in performance between baseline and comparison variants.

3. Its configuration does not mark it "erratic".

[wiyu]

/merge

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