[Lua] Change bind to use retail accurate random duration

[TracentEden2]

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• I understand that if I do not agree to the following points by completing the checkboxes my PR will be ignored.
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• 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?

This PR changes the duration of the spell bind and bindga to have a random duration (as on retail). I performed retail testing/captures that is summarized here for both player->mob and mob->player. Essentially, after discussing with some magic people, the current best estimation is bind duration is drawn from a normal distribution with mean of 30s, std. dev. of 12 seconds, min of 1 sec, and max of 60 seconds. The random nature of bind duration (along with the max duration) is further supported by JP wiki here.

Steps to test these changes

Bind mobs and watch the duration.