Qutrub skill changes for retail accuracy

[jmcmorris]

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• [x] I understand that if I do not agree to the following points by completing the checkboxes my PR will be ignored.
• [x] I understand I should leave resolving conversations to the LandSandBoat team so that reviewers won't miss what was said.
• [x] I have read and understood the Contributing Guide and the Code of Conduct.
• [x] I have tested my code and the things my code has changed since the last commit in the PR and will test after any later commits.

What does this pull request do?

Many changes made to Qutrub mob skills to make them more retail accurate. This is primarily based off of all the work Jimmayus did found in the following document: https://docs.google.com/spreadsheets/d/1YBoveP-weMdidrirY-vPDzHyxbEI2ryECINlfCnFkLI/edit?gid=57955395#gid=57955395

One of the larger changes here is the addition of a new function, xi.mobskills.calculateDuration, which simply calculates the duration giving the minimum/maximum and the TP which evenly lerps between the two as expected.

Steps to test these changes

Go fight a Qutrub (!gotoid 16998466) and test the various skills.