feat(dragonfly-client): add logs for finished piece from local

[gaius-qi]

Description

This pull request includes changes to optimize download behavior and improve logging in the dragonfly-client project. The most important changes involve reducing the default concurrent piece download count and adding logging for completed pieces.

Download behavior optimization:

• dragonfly-client-config/src/dfdaemon.rs: Reduced the default number of concurrent pieces to download from 16 to 8 to optimize resource usage and potentially improve stability.

Logging improvements:

• dragonfly-client/src/resource/piece.rs: Added info log statements to indicate when a piece or a persistent cache piece is finished and retrieved locally. This change appears in three locations within the impl Piece block. [1] [2] [3]

Related Issue

Motivation and Context

Screenshots (if appropriate)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 49.49%. Comparing base (5bc3a0a) to head (828ccb9).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1147   +/-   ##
=======================================
  Coverage   49.49%   49.49%           
=======================================
  Files          58       58           
  Lines       12075    12075           
=======================================
  Hits         5977     5977           
  Misses       6098     6098           

Files with missing lines	Coverage Δ
dragonfly-client-config/src/dfdaemon.rs	92.10% <100.00%> (ø)
dragonfly-client/src/resource/piece.rs	60.71% <ø> (ø)

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