remove indexed keyword from onlyOwner events

[StErMi]

It's true that those functions can be called only by the owner (that could still change) and having an indexed parameter will cost more gas (we are talking about really a little).

Removing that keyword makes the parameter not searchable. I would expect that monitoring tools would like to allow you to do that even if they are not indexed because they could index those events internally on their web2 DB.

@dannypostma do you think that it's a good tradeoff? I never used tools like Tenderly or OpenZeppelin Defender so the point before is only my assumptions on how I would do things on a web2 service.

Events where we could remove the indexed param:

• StakingFeeUpdated
• MaxSubscriptionsUpdated
• SubscriptionMonthPriceUpdated
• TreasuryWithdraw
• TreasuryUpdated
• StakingPayoutSent
• RareBlocksStakingUpdated