fix: honor klog -stderrthreshold even when -logtostderr is true

[pierluigilenoci]

What type of PR is this?

/kind bug

What this PR does / why we need it:

klog v2 defaults -logtostderr to true, which silently causes
-stderrthreshold to be ignored. This means operators cannot tune the
severity threshold for stderr output — every log line is already sent to
stderr regardless.

klog v2.140.0 introduced the legacy_stderr_threshold_behavior flag
(kubernetes/klog#432) to fix this. Setting it to false immediately
after klog.InitFlags restores proper -stderrthreshold semantics.

This PR:

1. Bumps k8s.io/klog/v2 from v2.130.1 → v2.140.0 in every
   go.mod (root, dev/tools/controllerbuilder, experiments/composite,
   experiments/tools/licensescan, mockgcp) and the root replace
   directive.
2. Patches every klog.InitFlags call site (10 files) to opt into
   the new behavior:
   • flag.Set("legacy_stderr_threshold_behavior", "false") /
     flag.Set("stderrthreshold", "INFO") for sites using the default
     flag.CommandLine
   • fs.Set(...) for sites using a custom flag.FlagSet
3. Leaves dev/tools/controllerbuilder/cmd/resourcerunner/main.go
   untouched — it imports klog v1, which doesn't have this flag.

Which issue(s) this PR fixes:

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

Does this PR introduce a user-facing change?

NONE

[google-oss-prow]

@pierluigilenoci: The label(s) kind/bug cannot be applied, because the repository doesn't have them.

Details

In response to this:

What type of PR is this?

/kind bug

What this PR does / why we need it:

klog v2 defaults -logtostderr to true, which silently causes
-stderrthreshold to be ignored. This means operators cannot tune the
severity threshold for stderr output — every log line is already sent to
stderr regardless.

klog v2.140.0 introduced the legacy_stderr_threshold_behavior flag
(kubernetes/klog#432) to fix this. Setting it to false immediately
after klog.InitFlags restores proper -stderrthreshold semantics.

This PR:

1. Bumps k8s.io/klog/v2 from v2.130.1 → v2.140.0 in every
   go.mod (root, dev/tools/controllerbuilder, experiments/composite,
   experiments/tools/licensescan, mockgcp) and the root replace
   directive.
2. Patches every klog.InitFlags call site (10 files) to opt into
   the new behavior:

• flag.Set("legacy_stderr_threshold_behavior", "false") /
  flag.Set("stderrthreshold", "INFO") for sites using the default
  flag.CommandLine
• fs.Set(...) for sites using a custom flag.FlagSet

3. Leaves dev/tools/controllerbuilder/cmd/resourcerunner/main.go
   untouched — it imports klog v1, which doesn't have this flag.

Which issue(s) this PR fixes:

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

Does this PR introduce a user-facing change?

NONE

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[google-oss-prow]

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