♻️ [RUM-6181] Use performanceObserver for LCP entries

[amortemousque]

Motivation

Following the introduction of performanceObservable to move away from performanceCollection: PR
Let use performanceObservable for LCP entries.

Changes

• Remove LCP from performanceCollection
• Use perfomanceObservable in trackLargestContentfulPaint

Testing

• Local
• Staging
• Unit
• End to end

---

I have gone over the contributing documentation.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.54%. Comparing base (a0d918c) to head (6f1ef52).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2990   +/-   ##
=======================================
  Coverage   93.54%   93.54%           
=======================================
  Files         273      273           
  Lines        7605     7605           
  Branches     1709     1709           
=======================================
  Hits         7114     7114           
  Misses        491      491           

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[cit-pr-commenter]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	0 B	161.34 KiB	161.34 KiB	N/A%	✅
Logs	0 B	56.12 KiB	56.12 KiB	N/A%	✅
Rum Slim	0 B	109.95 KiB	109.95 KiB	N/A%	✅
Worker	0 B	25.21 KiB	25.21 KiB	N/A%	✅

🚀 CPU Performance

Action Name	Base Average Cpu Time (ms)	Local Average Cpu Time (ms)	𝚫
addglobalcontext	N/A	0.002	0.002
addaction	N/A	0.042	0.042
addtiming	N/A	0.001	0.001
adderror	N/A	0.059	0.059
startstopsessionreplayrecording	N/A	0.933	0.933
startview	N/A	1.102	1.102
logmessage	N/A	0.021	0.021

🧠 Memory Performance

Action Name	Base Consumption Memory (bytes)	Local Consumption Memory (bytes)	𝚫 (bytes)
addglobalcontext	NaN KiB	8.39 KiB	NaN KiB
addaction	NaN KiB	38.77 KiB	NaN KiB
addtiming	NaN KiB	6.58 KiB	NaN KiB
adderror	NaN KiB	43.00 KiB	NaN KiB
startstopsessionreplayrecording	NaN KiB	4.84 KiB	NaN KiB
startview	NaN KiB	346.52 KiB	NaN KiB
logmessage	NaN KiB	40.64 KiB	NaN KiB

🔗 RealWorld