Corrects twig templates to use basic html in form help text

[volha-pivavarchyk]

Q	A
Bug fix? (use the a.b branch)	[✓]
New feature/enhancement? (use the a.x branch)	[✗ ]
Deprecations?	[ ✗ ]
BC breaks? (use the c.x branch)	[✗ ]
Automated tests included?	[✗ ]
Related user documentation PR URL	mautic/mautic-documentation#...
Related developer documentation PR URL	mautic/developer-documentation#...
Issue(s) addressed	Fixes #...

Description:

After migration to twig templates basic html code in form help text is not rendered.

It was added by PR #11335.

This PR fixes it.

Steps to test this PR:

1. Open this PR on Gitpod or pull down for testing locally (see docs on testing PRs here)
2. Create a new form.
3. Add a help message formatted with html tags.
4. Check if html code is rendered
5. Add a help message with a dangerous tag, e.g. script
6. Check if this tag is removed

[codecov]

Codecov Report

Merging #12562 (90dece8) into 5.x (9a609d5) will increase coverage by 0.07%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##                5.x   #12562      +/-   ##
============================================
+ Coverage     57.28%   57.35%   +0.07%     
- Complexity    33531    33533       +2     
============================================
  Files          2163     2163              
  Lines        101323   101330       +7     
============================================
+ Hits          58038    58119      +81     
+ Misses        43285    43211      -74     

see 10 files with indirect coverage changes

[escopecz]

Thanks! 👍