Changing regex to have a limit of characters allowed

[mboudreau]

What's in this PR? Adding character limit of 256 to the issue key regex to stop sending overly long issue keys to jira API

Why Because it was breaking something in Jira API/DSS and was requested by Sayians.

Added feature flags No need.

Affected issues
None

How has this been tested?
Unit test

Whats Next? Move issue key parsing/validation to Jira API ;)