fix(EraserBrush): visual trace while erasing

[ShaMan123]

A hack that reduces the path width while clipping the main context, resulting in a better visual overlap of both contexts
The issue's cause is unknown at time of writing - I don't understand why this is happening.

Added another minor change of the masking logic. Instead of source-over I reversed the order to use destination-in. Shouldn't affect anything and is simpler to grasp.

closes #7984

[github-actions]

Code Coverage Summary

> fabric@5.1.0 coverage:report
> nyc report --reporter=lcov --reporter=text

-----------|---------|----------|---------|---------|-----------------------------------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s                             
-----------|---------|----------|---------|---------|-----------------------------------------------
All files  |   83.05 |    75.98 |   85.69 |   82.78 |                                               
 fabric.js |   83.05 |    75.98 |   85.69 |   82.78 | ...,30850,30924,30935-31000,31123,31222,31458 
-----------|---------|----------|---------|---------|-----------------------------------------------

[github-actions]

Code Coverage Summary

> fabric@5.1.0 coverage:report
> nyc report --reporter=lcov --reporter=text

-----------|---------|----------|---------|---------|-----------------------------------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s                             
-----------|---------|----------|---------|---------|-----------------------------------------------
All files  |   83.05 |    75.98 |   85.69 |   82.78 |                                               
 fabric.js |   83.05 |    75.98 |   85.69 |   82.78 | ...,30850,30924,30935-31000,31123,31222,31458 
-----------|---------|----------|---------|---------|-----------------------------------------------

[github-actions]

Code Coverage Summary

> fabric@5.1.0 coverage:report
> nyc report --reporter=lcov --reporter=text

-----------|---------|----------|---------|---------|-----------------------------------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s                             
-----------|---------|----------|---------|---------|-----------------------------------------------
All files  |   83.05 |    75.98 |   85.69 |   82.78 |                                               
 fabric.js |   83.05 |    75.98 |   85.69 |   82.78 | ...,30850,30924,30935-31000,31123,31222,31458 
-----------|---------|----------|---------|---------|-----------------------------------------------

[github-actions]

Code Coverage Summary

> fabric@5.1.0 coverage:report
> nyc report --reporter=lcov --reporter=text

-----------|---------|----------|---------|---------|-----------------------------------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s                             
-----------|---------|----------|---------|---------|-----------------------------------------------
All files  |   83.05 |    75.98 |   85.69 |   82.78 |                                               
 fabric.js |   83.05 |    75.98 |   85.69 |   82.78 | ...,30850,30924,30935-31000,31123,31222,31458 
-----------|---------|----------|---------|---------|-----------------------------------------------

[ShaMan123]

This is ready.
Anyways it is not breaking because I've exposed the prop erasingWidthAliasing that can be set to 0 to revert to previous behavior.