`VoteKickPolicy._endVote()` might revert forever due to underflow
In `onFlag()`, `targetStakeAtRiskWei[target]` might be less than the total rewards for the flagger/reviewers due to rounding.\\n```\\nFile: contracts\\OperatorTokenomics\\StreamrConfig.sol\\n    /**\\n     * Minimum amount to pay reviewers+flagger\\n     * That is: minimumStakeWei >= (flaggerRewardWei + flagReviewerCount * flagReviewerRewardWei) / slashingFraction\\n     */\\n    function minimumStakeWei() public view returns (uint) {\\n        return (flaggerRewardWei + flagReviewerCount * flagReviewerRewardWei) * 1 ether / slashingFraction;\\n    }\\n```\\n\\nLet's assume `flaggerRewardWei + flagReviewerCount * flagReviewerRewardWei = 100, StreamrConfig.slashingFraction = 0.03e18(3%), minimumStakeWei() = 1000 * 1e18 / 0.03e18 = 10000 / 3 = 3333.`\\nIf we suppose `stakedWei[target] = streamrConfig.minimumStakeWei()`, then `targetStakeAtRiskWei[target]` = 3333 * 0.03e18 / 1e18 = 99.99 = 99.\\nAs a result, `targetStakeAtRiskWei[target]` is less than total rewards(=100), and `_endVote()` will revert during the reward distribution due to underflow.\\nThe above scenario is possible only when there is a rounding during `minimumStakeWei` calculation. So it works properly with the default `slashingFraction = 10%`.
Always round the `minimumStakeWei()` up.
The `VoteKickPolicy` wouldn't work as expected and malicious operators won't be kicked forever.
```\\nFile: contracts\\OperatorTokenomics\\StreamrConfig.sol\\n    /**\\n     * Minimum amount to pay reviewers+flagger\\n     * That is: minimumStakeWei >= (flaggerRewardWei + flagReviewerCount * flagReviewerRewardWei) / slashingFraction\\n     */\\n    function minimumStakeWei() public view returns (uint) {\\n        return (flaggerRewardWei + flagReviewerCount * flagReviewerRewardWei) * 1 ether / slashingFraction;\\n    }\\n```\\n