fix: xi.items is an invalid reference, remove duplicate quest code

[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?

Fixes xi.items references that should be xi.item. Most likely a result of porting code from ASB where they use xi.items. Also adds some missing item enums. Also removes duplicate old quest code now since these quests have been converted to the new framework, otherwise you get 2 rewards.

Steps to test these changes

1. !exec player:setFame(2, 1500)
2. !exec player:setFame(4, 1500)

The Sand Charm

1. !additem 13095 Sand Charm
2. !pos 23.118 -7.758 39.575 249 Blandine
3. !pos 31.511 -9.001 23.496 249 Zexu
4. !pos 23.118 -7.758 39.575 249 Blandine
5. !pos -37.624 -16.050 75.681 249 Celestina
6. /item "Sand Charm" on Celestina

Under The Sea

1. !pos -18.770 -2.597 -14.929 248 Yaya
2. !pos 47.119 -15.273 7.989 248 Oswald
3. !pos -17.342 -2.597 -18.766 248 Jimaida
4. !pos -11.810 -7.287 -6.742 Zaldon
5. !additem 4501 Fat Greedie
6. /item "Fat Greedie" on Zaldon
7. !pos 47.119 -15.273 7.989 248 Oswald once you get KI

The Gift

1. !additem 4375 Danceshroom
2. !pos 47.119 -15.273 7.989 248 Oswald
3. /item "Danceshroom" on Oswald

The Real Gift

1. !additem 4484 Shall Shell
2. !pos 47.119 -15.273 7.989 248 Oswald
3. /item "Shall Shell" on Oswald