Fix splitting of custom headers with custom marker in http malleable listener

[ruvolof]

Describe your changes

• Fixed headers splitting on commas, it now uses a custom marker as header end
• Removed no-op replace from http.ps1

Issue ticket number and link (if there is one)

#829

Checklist before requesting a review

• I have performed a self-review of my code
• [-] If it is a core feature, I have added thorough tests.
• I have added an entry to CHANGELOG.md
• [-] I have updated the documentation in docs/ (if applicable)