`FsEventScheduler::onAccessUpdateDecl` does a needless `getOwnerForFileId`

[icewind1991]

FsEventScheduler::onAccessUpdateDecl calls StorageService::getOwnerForFileId to get the owner. But all call sites of onAccessUpdateDecl already have the cached mount data, and can thus get the same data without having to fetch the info.

This ends up doing a bunch of extra load every time.