tools: support changing service-middleware config through pd-ctl

[rleungx]

What problem does this PR solve?

Issue Number: Close #4373

What is changed and how does it work?

show

config show service-middleware

set

config set service-middleware audit enable-audit false
config set service-middleware rate-limit GetRegion qps 100
config set service-middleware grpc-rate-limit GetRegion qps 100
config set service-middleware rate-limit GetRegion concurrency 10
config set service-middleware grpc-rate-limit GetRegion concurrency 10

detele

config set service-middleware rate-limit GetRegion qps 0
config set service-middleware grpc-rate-limit GetRegion qps 0
config set service-middleware rate-limit GetRegion concurrency 0
config set service-middleware grpc-rate-limit GetRegion concurrency 0

This PR supports using pd-ctl to manage the service middleware config.

Check List

Tests

• Unit test

Release note

None.

[codecov]

Codecov Report

Attention: Patch coverage is 88.00000% with 6 lines in your changes missing coverage. Please review.

Project coverage is 77.57%. Comparing base (642f0e9) to head (f30b042).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8645      +/-   ##
==========================================
+ Coverage   77.50%   77.57%   +0.06%     
==========================================
  Files         474      474              
  Lines       62311    62361      +50     
==========================================
+ Hits        48297    48377      +80     
+ Misses      10448    10417      -31     
- Partials     3566     3567       +1     

Flag	Coverage Δ
unittests	77.57% <88.00%> (+0.06%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lhy1024, nolouch

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [lhy1024,nolouch]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-09-23 12:35:13.460249804 +0000 UTC m=+1482983.200673742: ☑️ agreed by lhy1024.
• 2024-09-26 02:39:11.050612668 +0000 UTC m=+1706420.791036621: ☑️ agreed by nolouch.