Fix "BrowserExtensionInstalled" event logging
Created by: erzhtor
Closes https://github.com/sourcegraph/sourcegraph/issues/33143.
Turned out it was logging not only on initial install but every time URL is changed
Test plan
yarn --cwd client/browser dev
- Install browser extension locally
- Open browser extension background page and see the console log
Triggered "BrowserExtensionInstalled" using https://sourcegraph.com
- Change URL and check that there no more such console log messages
NOTE: For debug purposes 6b2208dd7a7882a0a42566ed962a35478727a4a5 code was added to only log to console, because there is no other way to see background page DevTools/Network tab initial (on install) requests