fix(registry/etcdv3): guard dataListener.interestedURL with RWMutex

[Aias00]

What

dataListener.interestedURL was a plain slice with no lock; AddInterestedURL appends from the DoSubscribe path while DataChange reads it (slices.ContainsFunc) on the etcd watch goroutine, racing the slice header.

Why

// registry/etcdv3/listener.go (before)
type dataListener struct {
    interestedURL []*common.URL   // no lock
    listener      config_center.ConfigurationListener
}
func (l *dataListener) AddInterestedURL(url *common.URL) {
    l.interestedURL = append(l.interestedURL, url)   // DoSubscribe path
}
func (l *dataListener) DataChange(eventType remoting.Event) bool {
    ...
    if slices.ContainsFunc(l.interestedURL, serviceURL.URLEqual) {  // etcd watch goroutine
        l.listener.Process(...)
    }
}

Two near-simultaneous DoSubscribe calls, or a subscribe concurrent with an incoming etcd watch event, race on the slice header → torn reads, missed event matching. go test -race flags it.

Fix

Add a sync.RWMutex to dataListener. AddInterestedURL takes the write lock; DataChange does the ContainsFunc check under RLock, releases it, then dispatches Process outside the lock.

Tests

Added Test_dataListener_ConcurrentAddAndDataChange: 100 rounds of concurrent AddInterestedURL vs DataChange, passing under -race. registry/etcdv3 passes under -race.

Fixes #3544

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 55.32%. Comparing base (60d1c2a) to head (86d0f7e).
⚠️ Report is 875 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3545      +/-   ##
===========================================
+ Coverage    46.76%   55.32%   +8.55%     
===========================================
  Files          295      462     +167     
  Lines        17172    36002   +18830     
===========================================
+ Hits          8031    19918   +11887     
- Misses        8287    14527    +6240     
- Partials       854     1557     +703     

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