fix(kuma-cp) Fix DP tracking lock consistency

[jpeach]

Summary

In the DataplaneLifecycle tracker, consistently lock the map that
tracks whether the dataplane has been successfully registered.

Full changelog

• Fix a crash when multiple Dataplanes register concurrently

Issues resolved

Fix 2566

Documentation

N/A

Testing

• Unit tests
• E2E tests
• Manual testing on Universal
• Manual testing on Kubernetes

Backwards compatibility

• Add backport-to-stable label if the code is backwards compatible. Otherwise, list breaking changes.

[codecov-commenter]

Codecov Report

Merging #2567 (733d6fa) into master (94c197e) will increase coverage by 0.01%.
The diff coverage is 84.61%.

@@            Coverage Diff             @@
##           master    #2567      +/-   ##
==========================================
+ Coverage   52.30%   52.32%   +0.01%     
==========================================
  Files         868      868              
  Lines       48296    48298       +2     
==========================================
+ Hits        25261    25270       +9     
+ Misses      20991    20983       -8     
- Partials     2044     2045       +1     

Impacted Files	Coverage Δ
pkg/xds/server/callbacks/dataplane_lifecycle.go	67.69% <84.61%> (+8.96%)	⬆️
pkg/core/resources/store/customizable_store.go	77.77% <0.00%> (-11.12%)	⬇️
pkg/plugins/resources/memory/store.go	77.71% <0.00%> (-4.35%)	⬇️
pkg/insights/resyncer.go	65.81% <0.00%> (+0.85%)	⬆️
pkg/xds/generator/direct_access_proxy_generator.go	83.90% <0.00%> (+1.14%)	⬆️
pkg/core/bootstrap/autoconfig.go	54.46% <0.00%> (+8.03%)	⬆️

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