don't send messages to all windows in onBeforeRequest

[bridiver]

Test plan

#9702 (comment)

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https://github.com/brave/browser-laptop/blob/master/app/filtering.js#L140

BrowserWindow.getAllWindows().forEach((wnd) =>
          wnd.webContents.send(message, parentResourceName, {
            tabId: details.tabId,
            url: details.url
          }))

is inefficient and wasteful because the message only needs to go to one tab
related #9678 (review)