fix(fabric.Text): fixes decoration rendering when there is a single rendering for the line

[asturur]

fixes #7076

Make sure the last iteration of the loop is rtl aware too.

[github-actions]

Code Coverage Summary

> fabric@4.5.0 coverage:report /home/runner/work/fabric.js/fabric.js
> nyc report --reporter=lcov --reporter=text

-----------|---------|----------|---------|---------|-----------------------------------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s                             
-----------|---------|----------|---------|---------|-----------------------------------------------
All files  |   82.94 |    76.98 |   85.75 |   82.64 |                                               
 fabric.js |   82.94 |    76.98 |   85.75 |   82.64 | ...,29686,29811,29891-29956,30079,30178,30395 
-----------|---------|----------|---------|---------|-----------------------------------------------