refactor(resource): add tracing to parent selector methods

[gaius-qi]

Description

This pull request adds tracing instrumentation to key methods in both the ParentSelector and PersistentCacheParentSelector implementations in dragonfly-client/src/resource/parent_selector.rs. The primary goal is to improve observability and debugging by enabling detailed tracing of method calls without logging their arguments.

Instrumentation for observability:

• Added the #[instrument(skip_all)] attribute to the following methods in ParentSelector:

  • select
  • register
  • unregister
  • get_idle_tx_bandwidth

• Added the #[instrument(skip_all)] attribute to the following methods in PersistentCacheParentSelector:

  • select
  • register
  • unregister
  • get_idle_tx_bandwidth

Related Issue

Motivation and Context

Screenshots (if appropriate)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 48.03%. Comparing base (504b7de) to head (97d8bc1).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1482      +/-   ##
==========================================
+ Coverage   47.53%   48.03%   +0.49%     
==========================================
  Files          70       70              
  Lines       17724    17540     -184     
==========================================
  Hits         8425     8425              
+ Misses       9299     9115     -184     

Files with missing lines	Coverage Δ
dragonfly-client/src/resource/parent_selector.rs	0.00% <ø> (ø)

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