[Magic] Fix Flurry and Haste overwrites and Flurry self stack

[ampitere]

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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?

Currently players can stack Flurry and Haste but this should not be possible as they overwrite each other.

https://wiki.ffo.jp/html/644.html https://wiki.ffo.jp/html/31588.html

It also seems Flurry is using the wrong effect as there are 2 types of Flurry (at least in English, in Japanese Flurry is called Snap). The 265 effect actually seems to be the Nyzul specific version of Flurry which does not have any duration and I believe is the reason the duration does not properly display for Flurry. It also cannot be removed if you attempt to do so. As a result Flurry and Flurry II will no longer be stackable, I couldn't find documentation on whether they do stack but since it works similarly to Haste I can only assume that you cannot have both effects at the same time.

https://wiki.ffo.jp/html/11145.html

Before (Flurry and Flurry II stacking)

After

This fixes the 1st and 3rd issue on https://github.com/LandSandBoat/server/issues/669. The 2nd issue should already be resolved from what I can tell.

Steps to test these changes

1. !changejob 5 99
2. !addallspells
3. Cast Haste
4. Cast Flurry, it should overwrite Haste (!getmod snap_shot should give 15)
5. Cast Haste, it should overwrite Flurry
6. Cast Flurry II, it should overwrite Haste (!getmod snap_shot should give 30)
7. Cast Flurry, it should have no effect (!getmod snap_shot should still give 30)

[Xaver-DaRed]

This will need retail captures.

Not asking you to do it.