Replace arc-swap with hazarc

[wyfo]

Description

Replace arc-swap with hazarc

What does this PR do?

Replace arc-swap with hazarc

Why is this change needed?

hazarc has better performance characteristic, especially regarding loading of None and is more robustly tested.

Related Issues

None

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🏷️ Label-Based Checklist

Based on the labels applied to this PR, please complete these additional requirements:

Labels: dependencies, internal

📦 Dependency Updates

Since this PR updates dependencies:

• Changelog reviewed - Breaking changes in dependency identified and addressed
• Security advisories checked - No known vulnerabilities in new version
• License compatible - New version license is compatible with project
• Tests pass - All tests pass with new dependency versions
• Transitive deps reviewed - New transitive dependencies checked
• Version pinned appropriately - Semver range is intentional and correct
• Update scope limited - Updating one major dependency at a time when possible

Best practice: Keep dependency updates focused and test thoroughly.

🏠 Internal Change

This PR is marked as internal (not user-facing):

• No API changes - Public APIs unchanged
• No behavior changes - External behavior identical
• Refactoring/maintenance - Code improvements only
• Tests still pass - All existing tests pass without modification

Lighter review: Internal changes may have lighter review requirements.

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[codecov]

Codecov Report

❌ Patch coverage is 86.56716% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.58%. Comparing base (9f8dff1) to head (ccba348).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
zenoh/src/net/routing/dispatcher/face.rs	57.14%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2472      +/-   ##
==========================================
- Coverage   72.60%   72.58%   -0.03%     
==========================================
  Files         390      390              
  Lines       63374    63364      -10     
==========================================
- Hits        46015    45990      -25     
- Misses      17359    17374      +15     

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[fuzzypixelz]

I think two things are worth discussing:

1. Is there evidence to support the claim of better performance for zenoh's use case(s)?
2. How confident are we that hazarc—being a relatively new crate—is battle-tested and proven? Admittedly, it already has one reverse dependency on crates.io. So I searched for the circumstances that led the project chose to use hazarc hoping for a independent analysis, but alas all I found was a pull request titled "Performance fix" where the author replaces RwLock with hazarc::AtomicArc without citing their reasoning.

If your answer to (1) is convincing enough (i.e. we stand to gain a lot), I'd be willing to take a risk and ignore (2) since I have good confidence in your work.

Ideally, I would need to do a deep-dive into hazarc myself to answer (2) but I am no expert on the topic and would need to spend significant time and effort to build up a good understanding of the design space.

With no peformance data, no independent analysis of hazarc's design and implementation and little time to commit to doing an analysis myself in the near future, I am not in a position to review nor merge this pull request.