chore: optimize comments of the ParentSelector config

[gaius-qi]

Description

This pull request includes several updates and improvements to the dfdaemon.rs file in the dragonfly-client-config module. The changes primarily focus on refining the ParentSelector configuration and updating associated documentation.

Refinements to ParentSelector Configuration:

• Added default_parent_selector_sync_interval and default_parent_selector_capacity functions to set default values for the sync interval and capacity of the parent selector.
• Removed redundant definitions of default_parent_selector_sync_interval and default_parent_selector_capacity to avoid duplication. [1] [2]

Documentation Updates:

• Updated comments to clarify the functionality and purpose of the ParentSelector and its fields, including the sync interval and capacity. [1] [2]

Related Issue

dragonflyoss/dragonfly#3713

Motivation and Context

Screenshots (if appropriate)

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.

Project coverage is 34.58%. Comparing base (3d91c09) to head (46ca0f9).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
dragonfly-client-config/src/dfdaemon.rs	0.00%	6 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #927   +/-   ##
=======================================
  Coverage   34.58%   34.58%           
=======================================
  Files          60       60           
  Lines        9308     9308           
=======================================
  Hits         3219     3219           
  Misses       6089     6089           

Files with missing lines	Coverage Δ
dragonfly-client-config/src/dfdaemon.rs	48.65% <0.00%> (ø)

[fcgxz2003]

LGTM

[chlins]

lgtm