Migrate to klog/v2 v2.140.0 and honor stderrthreshold when logtostderr is enabled

[pierluigilenoci]

Summary

• Migrate all direct k8s.io/klog (v1) imports to k8s.io/klog/v2 and bump to v2.140.0 which includes the fix for stderrthreshold not honored when logtostderr is set kubernetes/klog#212.
• Opt into the new klog behavior by setting -legacy_stderr_threshold_behavior=false so that -stderrthreshold is honored even when -logtostderr=true (the klog default).
• Set stderrthreshold=INFO to preserve backward-compatible behavior (all logs still appear on stderr by default). Users can now override -stderrthreshold to WARNING or ERROR to reduce stderr noise.
• Wire klog flags into pflag.CommandLine in cmd/olm/main.go so that klog flags (like -v, -stderrthreshold) are actually accessible from the command line (they were previously registered but never parsed).
• Fix klog v1→v2 API incompatibility: klog.V() returns Verbose struct in v2 (not bool) — use .Enabled() for conditional checks.

This addresses #2131 where all OLM logs are classified as ERROR by log aggregation systems (DataDog, CloudWatch, GCP Cloud Logging) because everything is unconditionally written to stderr regardless of severity.

Background

When -logtostderr=true (klog's default), the -stderrthreshold flag was completely ignored — all log levels were written to stderr. Log aggregation systems that infer severity from the output stream (stdout=INFO, stderr=ERROR) would misclassify every OLM log message as an error.

klog v2.140.0 (kubernetes/klog#432) introduced a fix behind the -legacy_stderr_threshold_behavior flag. Setting it to false enables proper severity-based filtering on the stderr path.

The stderrthreshold=INFO default preserves existing behavior (all logs on stderr), while giving operators the ability to set -stderrthreshold=WARNING or -stderrthreshold=ERROR to only send higher-severity messages to stderr.

Test plan

• Existing unit tests pass
• Deploy with default configuration — all logs appear on stderr (backward compatible)
• Deploy with -stderrthreshold=WARNING — only WARNING and above appear on stderr

Fixes #2131

Ref: kubernetes/klog#212, kubernetes/klog#432

[openshift-ci]

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[openshift-ci]

Hi @pierluigilenoci. Thanks for your PR.

I'm waiting for a operator-framework member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work.

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[pierluigilenoci]

cc @joelanford @kevinrizza @perdasilva — would you be able to review this when you get a chance? This PR migrates from klog v1 to v2 and opts into the klog fix for kubernetes/klog#212 so that -stderrthreshold is honored even when -logtostderr=true. Related: operator-framework/operator-lifecycle-manager#2131. The PR also needs /ok-to-test from an org member to run CI.