enhance: Introduce batch subscription in msgdispatcher

[bigsheeper]

Introduce a batch subscription mechanism in msgdispatcher: the msgdispatcher now includes a vchannel watch task queue, where all vchannels in the queue will subscribe to the MQ only once and pull messages from the oldest vchannel checkpoint to the latest.

issue: #39862

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.58%. Comparing base (c917fe4) to head (e288697).
Report is 1 commits behind head on master.

❗ Current head e288697 differs from pull request most recent head 606b824

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❌ Your project check has failed because the head coverage (69.58%) is below the target coverage (77.00%). You can increase the head coverage or adjust the target coverage.

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HEAD has 2 uploads less than BASE

Flag	BASE (c917fe4)	HEAD (e288697)
	3	1

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #39863       +/-   ##
===========================================
- Coverage   79.76%   69.58%   -10.19%     
===========================================
  Files        1500      305     -1195     
  Lines      207393    27344   -180049     
===========================================
- Hits       165435    19027   -146408     
+ Misses      35927     8317    -27610     
+ Partials     6031        0     -6031     

Components	Coverage Δ
Client	∅ <ø> (∅)
Core	69.58% <ø> (-0.05%)	⬇️
Go	∅ <ø> (∅)

see 1205 files with indirect coverage changes

[bigsheeper]

/run-cpu-e2e

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[bigsheeper]

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