Fix remaining ES5 built-ins/RegExp tests

[HalidOdat]

It changes the following:

• Fix remaining ES5 built-ins/RegExp tests
• Don't allocate on every match check

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	93,990	93,990	0
Passed	74,603	74,605	+2
Ignored	17,489	17,489	0
Failed	1,898	1,896	-2
Panics	0	0	0
Conformance	79.37%	79.38%	+0.00%

Fixed tests (2):

test/built-ins/RegExp/S15.10.2.7_A2_T1.js [strict mode] (previously Failed)
test/built-ins/RegExp/S15.10.2.7_A2_T1.js (previously Failed)

[codecov]

Codecov Report

Merging #2957 (e8a36d6) into main (fdf9444) will decrease coverage by 0.24%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #2957      +/-   ##
==========================================
- Coverage   50.39%   50.15%   -0.24%     
==========================================
  Files         444      446       +2     
  Lines       45349    45761     +412     
==========================================
+ Hits        22854    22953      +99     
- Misses      22495    22808     +313     

Impacted Files	Coverage Δ
boa_engine/src/builtins/regexp/mod.rs	63.54% <100.00%> (+0.05%)	⬆️

... and 48 files with indirect coverage changes