feat: Configure Session Replay to wait for DOMContentLoaded

[metal-messiah]

Decrease the time spent waiting by triggering Session Replay mutation observer wrapping on the DOMContentLoaded event instead of the previously used window load event. This ensures wrapping is completed before the load chain.

Overview

Related Issue(s)

NR-300929

Testing

[github-actions]

Asset Size Report

Merging this pull request will result in the following asset size changes:

Agent	Asset	Previous Size	New Size	Diff
lite	loader	32.58 kB / 11.35 kB (gzip)	32.58 kB / 11.35 kB (gzip)	0% / 0% (gzip)
lite	async-chunk	50.46 kB / 16.25 kB (gzip)	50.46 kB / 16.25 kB (gzip)	0% / 0% (gzip)
pro	loader	53.64 kB / 18.08 kB (gzip)	53.64 kB / 18.08 kB (gzip)	0% / 0% (gzip)
pro	async-chunk	98.79 kB / 29.49 kB (gzip)	98.79 kB / 29.49 kB (gzip)	0% / 0% (gzip)
spa	loader	61.6 kB / 20.51 kB (gzip)	61.6 kB / 20.51 kB (gzip)	0% / 0% (gzip)
spa	async-chunk	113.88 kB / 33.82 kB (gzip)	113.88 kB / 33.82 kB (gzip)	0% / 0% (gzip)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.75%. Comparing base (4292f00) to head (210ee3e).
Report is 31 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1164      +/-   ##
==========================================
+ Coverage   87.83%   88.75%   +0.92%     
==========================================
  Files         162      165       +3     
  Lines        7291     7374      +83     
  Branches     1435     1636     +201     
==========================================
+ Hits         6404     6545     +141     
+ Misses        770      720      -50     
+ Partials      117      109       -8     

Flag	Coverage Δ
unit-tests	79.20% <ø> (+2.76%)	⬆️

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