Special chars in notifications are HTML encoded

Summary

When notification contains special character such as > or ", only its HTML entity is sent to the notification API (when a pipeline of MR javascript->typescript finishes, a notification with javascript->typescript is sent

Steps to reproduce

Simply create a MR with special chars and let the pipeline finish

What is the current bug behavior?

special chars are encoded as html entities

What is the expected correct behavior?

special chars should not be encoded as html entities

Output of checks

this is not happening on gitlab.com, but on selfhosted gitlab 12.4.1-ee