refactor: update initiator.go

[derekbit]

Which issue(s) this PR fixes:

Issue longhorn/longhorn#7124

What this PR does / why we need it:

1. Update log messages
2. Reimplement the retry logics using avast/retry-go

Special notes for your reviewer:

Additional documentation or context

[codecov]

Codecov Report

❌ Patch coverage is 14.35897% with 167 lines in your changes missing coverage. Please review.
✅ Project coverage is 2.73%. Comparing base (fdb3e3d) to head (1f212a7).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/initiator/initiator.go	15.13%	156 Missing and 1 partial ⚠️
pkg/spdk/client/advanced.go	0.00%	10 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##            main    #265      +/-   ##
========================================
+ Coverage   0.00%   2.73%   +2.73%     
========================================
  Files         38      38              
  Lines       4919    5017      +98     
========================================
+ Hits           0     137     +137     
+ Misses      4919    4870      -49     
- Partials       0      10      +10     

Flag	Coverage Δ
unittests	2.73% <14.35%> (+2.73%)	⬆️

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[Copilot]

Pull request overview

This PR refactors initiator retry behavior to use github.com/avast/retry-go/v4, updates related log messages, and adds test coverage around initiator validation and a few helper behaviors.

Changes:

• Add and vendor github.com/avast/retry-go/v4 and update go.mod/go.sum accordingly.
• Refactor NVMe/TCP retry loops (connect, disconnect wait, device-info loading, device creation validation) to use retry-go with fixed delays and retry logging.
• Add/expand initiator unit tests and add additional SPDK client log messages.

Reviewed changes

Copilot reviewed 4 out of 17 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
.gitignore	Ignore Dockerfile.dapper[0-9]*.
go.mod	Add github.com/avast/retry-go/v4 v4.7.0.
go.sum	Add checksums for retry-go and update other sums.
pkg/initiator/initiator.go	Replace manual retry loops with retry-go; update NVMe/TCP log messages; adjust ublk startup flow and disk creation validation.
pkg/initiator/initiator_test.go	Add unit tests for initiator validation and selected helper behaviors.
pkg/spdk/client/advanced.go	Add Info-level logs around expose/unexpose steps.
vendor/modules.txt	Record new vendored module entry.
vendor/github.com/avast/retry-go/v4/retry.go	Vendored retry-go implementation.
vendor/github.com/avast/retry-go/v4/options.go	Vendored retry-go options/config implementation.
vendor/github.com/avast/retry-go/v4/README.md	Vendored upstream documentation.
vendor/github.com/avast/retry-go/v4/LICENSE	Vendored upstream license.
vendor/github.com/avast/retry-go/v4/VERSION	Vendored upstream version marker.
vendor/github.com/avast/retry-go/v4/Makefile	Vendored upstream build tooling.
vendor/github.com/avast/retry-go/v4/.gitignore	Vendored upstream ignore file.
vendor/github.com/avast/retry-go/v4/.godocdown.tmpl	Vendored upstream doc template.
vendor/github.com/avast/retry-go/v4/generic.txt	Vendored upstream benchmark output.
vendor/github.com/avast/retry-go/v4/current.txt	Vendored upstream benchmark output.

Comments suppressed due to low confidence (1)

pkg/initiator/initiator.go:506

• StartUblkInitiator no longer initializes the ublk target (previously done via UblkCreateTarget). If the SPDK ublk target hasn't already been created elsewhere, subsequent UblkGetDisks / UblkStartDisk calls can fail. Consider ensuring the target exists here (create-once semantics, ignoring an "already exists" response if applicable) to preserve prior behavior.

	ublkDeviceList, err := spdkClient.UblkGetDisks(0)
	if err != nil {
		return false, err
	}

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 17 changed files in this pull request and generated 2 comments.

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[shuo-wu]

In general LGTM

[shuo-wu]

LGTM