fix(DB/Creature) Fel Crystals no longer follow players.

[Rorschach91]

This fix should resolve some issues with Fel Crystals during Selin Fireheart fight.
New Flags has been sniffed from Cata Classic.
Fel Crystals don't follow the players anymore (rooted flag).
Unit flags has been changed after the sniff (it seems they only have stunned and not selectable flags on official servers).
With the script change Fel Crystals don't turn in the direction of the first in threat player anymore.

Changes Proposed:

This PR proposes changes to:

• Core (units, players, creatures, game systems).
• Scripts (bosses, spell scripts, creature scripts).
• Database (SAI, creatures, etc).

Issues Addressed:

• Closes [Magister's Terrace] Fel Crystal target and chase players #21226

SOURCE:

The changes have been validated through:

• Live research (checked on live servers, e.g Classic WotLK, Retail, etc.)
• Sniffs (remember to share them with the open source community!)
• Video evidence, knowledge databases or other public sources (e.g forums, Wowhead, etc.)
• The changes promoted by this pull request come partially or entirely from another project (cherry-pick). Cherry-picks must be committed using the proper --author tag in order to be accepted, thus crediting the original authors, unless otherwise unable to be found

Tests Performed:

This PR has been:

• Tested in-game by the author.
• Tested in-game by other community members/someone else other than the author/has been live on production servers.
• This pull request requires further testing and may have edge cases to be tested.

How to Test the Changes:

• This pull request can be tested by following the reproduction steps provided in the linked issue
• This pull request requires further testing. Provide steps to test your changes. If it requires any specific setup e.g multiple players please specify it as well.

Known Issues and TODO List:

• [ ]
• [ ]

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