[CONTINT-3889] add common container registry config for admission controller

[adel121]

What does this PR do?

This PR adds a config to set a common container registry to be used by admission controller webhooks.

Motivation

The APM, CWS, and agent-sidecar webhooks in the admission controller have a “container_registry” option. It defaults to “gcr.io/datadoghq” in all cases:

• admission_controller.auto_instrumentation.container_registry
• admission_controller.cws_instrumentation.container_registry
• admission_controller.agent_sidecar.container_registry

The goal is to define an option that applies to all of them (i.e. admission_controller.container_registry) so it doesn’t need to be specified 3 times.

Additional Notes

• We don't remove the existing webhook-specific container registry config options in order to preserve backward compatibility.
• If a webhook wants to use a distinct container registry, it can define it is own config and use it instead of using the common container registry.

Possible Drawbacks / Trade-offs

Describe how to test/QA your changes

Ensure that the following webhooks are still working even when registry is not set for each one of them:

• agent sidecar
• SSI
• CWS instrumentation

[pr-commenter[bot]]

Bloop Bleep... Dogbot Here

Regression Detector Results

Run ID: 65b823a8-993b-40a9-aab7-705cdf7e1ffa Baseline: af00e79336597e0723c1e20dfe6eaf25a4e13e78 Comparison: 982e2dbf93dffc4a47becb924baffb1a98277ecf

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	-1.62	[-8.12, +4.89]

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI
➖	basic_py_check	% cpu utilization	+1.34	[-0.87, +3.56]
➖	otel_to_otel_logs	ingress throughput	+0.68	[+0.02, +1.34]
➖	process_agent_real_time_mode	memory utilization	+0.26	[+0.23, +0.30]
➖	tcp_syslog_to_blackhole	ingress throughput	+0.22	[+0.17, +0.28]
➖	idle	memory utilization	+0.18	[+0.14, +0.21]
➖	process_agent_standard_check	memory utilization	+0.04	[+0.01, +0.06]
➖	tcp_dd_logs_filter_exclude	ingress throughput	+0.00	[-0.00, +0.00]
➖	uds_dogstatsd_to_api	ingress throughput	-0.00	[-0.00, +0.00]
➖	trace_agent_json	ingress throughput	-0.00	[-0.03, +0.02]
➖	process_agent_standard_check_with_stats	memory utilization	-0.00	[-0.03, +0.02]
➖	trace_agent_msgpack	ingress throughput	-0.01	[-0.03, +0.01]
➖	file_tree	memory utilization	-0.08	[-0.15, -0.00]
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	-0.41	[-1.85, +1.04]
➖	file_to_blackhole	% cpu utilization	-1.62	[-8.12, +4.89]

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".

[adel121]

/merge

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