🐛 Improve context properties sanitization

[amortemousque]

Motivation

Certain context properties like usr.id and usr.name are converted to strings. This PR stops converting undefined and null values to strings, aligning the behavior with other context properties.

ex:

DD_RUM.setUser({ id: null, name: undefined })

Before	After
{ "id": "null", "name": "undefined", }	{ }

Changes

Testing

• Local
• Staging
• Unit
• End to end

---

I have gone over the contributing documentation.

[BenoitZugmeyer]

💬 suggestion: isNullish is not very explicit. Maybe rename to isDefined?

[cit-pr-commenter]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	0 B	145.14 KiB	145.14 KiB	N/A%	✅
Rum.recorder	0 B	18.02 KiB	18.02 KiB	N/A%	✅
Rum.profiler	0 B	4.64 KiB	4.64 KiB	N/A%	✅
Logs	0 B	50.20 KiB	50.20 KiB	N/A%	✅
Rum Slim	0 B	104.68 KiB	104.68 KiB	N/A%	✅
Worker	0 B	23.59 KiB	23.59 KiB	N/A%	✅

🚀 CPU Performance

Action Name	Base Average Cpu Time (ms)	Local Average Cpu Time (ms)	𝚫
addglobalcontext	0.003	0.004	0.000
addaction	0.046	0.063	0.017
addtiming	0.001	0.002	0.000
adderror	0.050	0.066	0.016
startstopsessionreplayrecording	0.009	0.015	0.007
startview	0.423	0.567	0.144
logmessage	0.020	0.029	0.009

🧠 Memory Performance

Action Name	Base Consumption Memory (bytes)	Local Consumption Memory (bytes)	𝚫 (bytes)
addglobalcontext	26.29 KiB	26.75 KiB	467 B
addaction	56.40 KiB	54.64 KiB	-1803 B
addtiming	23.58 KiB	23.79 KiB	216 B
adderror	59.77 KiB	58.46 KiB	-1338 B
startstopsessionreplayrecording	24.50 KiB	23.13 KiB	-1406 B
startview	430.05 KiB	426.00 KiB	-4150 B
logmessage	61.73 KiB	51.28 KiB	-10704 B

🔗 RealWorld

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.99%. Comparing base (66ce71d) to head (4158a43).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3475   +/-   ##
=======================================
  Coverage   91.98%   91.99%           
=======================================
  Files         310      310           
  Lines        8026     8028    +2     
  Branches     1820     1821    +1     
=======================================
+ Hits         7383     7385    +2     
  Misses        643      643           

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