[RUMF-857] round CLS to 4 decimals

[BenoitZugmeyer]

Motivation

Having more than 4 decimals to the cumulative layout shift score produce more noise than value. Since this score is compared to minimum 0.1, the precision is still 3 orders of magnitude below, so it should be completly fine.

Changes

Round the cumulative layout shift score to 4 decimals.

Testing

Unit

---

I have gone over the contributing documentation.

[codecov-io]

Codecov Report

Merging #773 (184214e) into master (4458339) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #773   +/-   ##
=======================================
  Coverage   86.48%   86.48%           
=======================================
  Files          76       76           
  Lines        3573     3574    +1     
  Branches      820      821    +1     
=======================================
+ Hits         3090     3091    +1     
  Misses        483      483           

Impacted Files	Coverage Δ
packages/core/src/tools/utils.ts	89.40% <100.00%> (ø)
.../src/domain/rumEventsCollection/view/trackViews.ts	97.38% <100.00%> (+0.01%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 4458339...184214e. Read the comment docs.