JBI slash escaping some characters when sending summary field data into Jira

[alexcottner]

JBI is markdown converting the summary field from bugzilla, causing some slash escapes in characters (examples below). But this field should never be markdown as it's plain text.

Bugzilla summary field is: [Foo]
Jira summary field becomes: \[Foo\]

Proposed solution: In update_issue_summary, remove markdown_to_jira call. Just truncate if we exceed the max length.