Raise issuable text limits
The 16,000 and 48,000-byte description and description HTML limits were a bit too low. In some of our onboarding tasks, the text took close to 170K.
Our API limits the description to be 1 megabyte, so update the limit to match that. From !16181 (merged), the estimated description HTML multiple was 3x, so make this limit 5x to give some leeway.
Edited by Thong Kuah