fix: Prevent leader checker from generating excessive duplicate leader tasks

[weiliu1031]

issue: #39001
Background:
Segment Load Version: Each segment load request assigns a timestamp as its version. When multiple copies of a segment are loaded on different QueryNodes, the leader checker uses this version to identify the latest copy and updates the routing table in the leader view to point to it. Delegator Router Version: When a delegator builds a route to a QueryNode that has loaded a segment, it also records the segment's version.

Router Table Update Logic: If the leader checker detects that the version of a segment in the routing table does not match the version in the worker, it updates the routing table to point to the QueryNode with the latest version. Additionally, it updates the segment's load version in the QueryNode during this process.

Issue:
When a channel is undergoing load balancing, the leader checker may sync the routing table to a new delegator. This sync operation modifies the segment's load version, which invalidates the routing in the old delegator. Subsequently, the leader checker updates the routing table in the old delegator, breaking the routing in the new delegator. This cycle continues, causing repeated updates and inconsistencies.

Fix:
This PR introduces two changes to address the issue:

1. Use NodeID to verify whether the delegator's routing table needs an update, avoiding unnecessary modifications.
2. Ensure compatibility by using the latest segment's load version as the version recorded in the routing table.

These changes resolve the cyclic updates and prevent the leader checker from generating excessive duplicate tasks, ensuring routing stability across delegators during load balancing.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.17%. Comparing base (d6206ad) to head (316f3a6).
Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #39000       +/-   ##
===========================================
+ Coverage   69.64%   81.17%   +11.52%     
===========================================
  Files         296     1390     +1094     
  Lines       26633   196782   +170149     
===========================================
+ Hits        18548   159728   +141180     
- Misses       8085    31466    +23381     
- Partials        0     5588     +5588     

Components	Coverage Δ
Client	79.53% <ø> (∅)
Core	69.64% <ø> (ø)
Go	83.11% <100.00%> (∅)

Files with missing lines	Coverage Δ
internal/querycoordv2/checkers/leader_checker.go	96.91% <100.00%> (ø)

... and 1093 files with indirect coverage changes

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