refactor(proxy): refactor DeadLetterService

[ShadowySpirits]

No description provided.

[codecov]

Codecov Report

Merging #811 (f8ac554) into main (5a1cdf8) will decrease coverage by 0.06%.
The diff coverage is 57.57%.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #811      +/-   ##
============================================
- Coverage     55.36%   55.31%   -0.06%     
- Complexity     1230     1232       +2     
============================================
  Files           132      132              
  Lines          8447     8433      -14     
  Branches        773      771       -2     
============================================
- Hits           4677     4665      -12     
  Misses         3366     3366              
+ Partials        404      402       -2     

Components	Coverage Δ
RocketMQ Broker	∅ <ø> (∅)
RocketMQ Common	5.80% <ø> (ø)
RocketMQ Controller	55.13% <ø> (ø)
RocketMQ Proxy	36.63% <57.57%> (-0.37%)	⬇️
RocketMQ Store	74.29% <ø> (ø)
RocketMQ Stream	∅ <ø> (∅)
RocketMQ Metadata	35.44% <ø> (ø)

Files	Coverage Δ
...tomq/rocketmq/proxy/service/DeadLetterService.java	74.57% <57.57%> (-7.62%)	⬇️

... and 3 files with indirect coverage changes