InterestRouterV2::triggerDistribution() may be vulnerable to arbitrage stratregies due to being permissionless

Description:

InterestRouterV2::triggerDistribution() is permissionless and may add significant rewards to the external contracts. In this process, arbitragers could employ arbitrage strategies, such as depositing, calling InterestRouterV2::triggerDistribution() and then withdrawing, stealing most of the rewards.

Recommended Mitigation:

While curve gauges are not vulnerable to this as rewards are distributed over 1 week, it is something to keep in mind, even more so because other strategies could be used in the future that are vulnerable.

0xSimao:

Fixed in #9f2906b.