Limit output in Jira Comment

[BhaaLseN]

Jira Comments are limited to 32767 characters, so very verbose merge failures may not make it:

GitMerger.IssueTracking.JiraBasicRestClient: Request to 'http://jira-server/rest/api/2/issue/JRA-1234/comment' apparently failed: The remote server returned an error: (400) Bad Request.
{"errorMessages":[],"errors":{"comment":"The entered text is too long. It exceeds the allowed limit of 32767 characters."}}

This should probably be one or more of those things:

• Limit the number of charaters for output (each of them) and truncate them either way (best is probably to keep the front parts?)
• Limit the total length of the comment and try to re-trim parts if necessary
• Retry with a shorter/different comment when it fails (because right now, only the log file has the error)