[Audit Fix] `SafeMath.pow(10, 18)` in `ElasticMath.revamp` should be hardcoded

[dmvt]

SafeMath.pow(10, 18) in ElasticMath.revamp is a very expensive exponentiation that should be hardcoded to 1e18.

Definition of Done

• SafeMath.pow is removed
• instances of Safemath.pow are replaced with 1e18

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