test/bbr: fix startup race condition and IPv6 address formatting

[LukeAVanDrie]

What type of PR is this?
/kind flake

What this PR does / why we need it:

This PR fixes a race condition in the Body-Based Routing (BBR) integration test harness that caused intermittent connect: connection refused failures in CI.

The Problem:
The test harness spawned the BBR server in a goroutine and immediately attempted to dial it via grpc.NewClient. In CI environments, the main test thread may execute the dial attempt before the server goroutine could initialize and successfully bind the TCP socket via net.Listen.

The Fix:

1. Readiness Polling: Implements a require.Eventually loop that attempts to net.Dial the target address. The test now blocks until the OS confirms the socket is open and listening before proceeding to gRPC initialization.
2. IPv6 Safety: Replaces manual string formatting (fmt.Sprintf("%s:%d")) with net.JoinHostPort. This ensures that IPv6 addresses returned by GetFreePort (e.g., ::1) are correctly bracketed (e.g., [::1]:port), preventing "too many colons in address" errors on dual-stack CI hosts.

Verified with:

go test ./test/integration/bbr/... \
  -run "TestFullDuplexStreamed_BodyBasedRouting" \
  -count 100 \
  -failfast \
  -v

Which issue(s) this PR fixes:
TODO: flake report not filed yet. Will link it shortly.

Does this PR introduce a user-facing change?:

NONE

[k8s-ci-robot]

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

Details

In response to this:

What type of PR is this?
/kind flake
/kind test

What this PR does / why we need it:

This PR fixes a race condition in the Body-Based Routing (BBR) integration test harness that caused intermittent connect: connection refused failures in CI.

The Problem:
The test harness spawned the BBR server in a goroutine and immediately attempted to dial it via grpc.NewClient. In CI environments, the main test thread may execute the dial attempt before the server goroutine could initialize and successfully bind the TCP socket via net.Listen.

The Fix:

1. Readiness Polling: Implements a require.Eventually loop that attempts to net.Dial the target address. The test now blocks until the OS confirms the socket is open and listening before proceeding to gRPC initialization.
2. IPv6 Safety: Replaces manual string formatting (fmt.Sprintf("%s:%d")) with net.JoinHostPort. This ensures that IPv6 addresses returned by GetFreePort (e.g., ::1) are correctly bracketed (e.g., [::1]:port), preventing "too many colons in address" errors on dual-stack CI hosts.

Verified with:

go test ./test/integration/bbr/... \
 -run "TestFullDuplexStreamed_BodyBasedRouting" \
 -count 100 \
 -failfast \
 -v

Which issue(s) this PR fixes:
TODO: flake report not filed yet. Will link it shortly.

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-sigs/prow repository.

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[k8s-ci-robot]

Hi @LukeAVanDrie. Thanks for your PR.

I'm waiting for a github.com 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. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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Details

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-sigs/prow repository.

[ahg-g]

/ok-to-test

[ahg-g]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ahg-g, LukeAVanDrie

The full list of commands accepted by this bot can be found here.

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Details

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• OWNERS [ahg-g]

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