Fix gem check being rolled twice.

giveGem roll is not needed in obtainGem because it is already checked in order to call obtainGem.

https://github.com/2006rebotted/2006rebotted/blob/15ab6253499e5f5a38372a296d35aa30492dd6d6/2006Redone%20Server/src/main/java/com/rebotted/game/content/skills/core/Mining.java#L232-L238

Calling random inside the Glory loop results in multiple rolls, potentially hiding the double giveGem check.