If rolling upgrade was used from version prior GeoIPv2 (<`7.14`) then
geoip downloader wouldn't be started so no new databases were
downloaded. This is especially troubling in `8.x` as we no longer
provide default databases inside ES so after upgrade no geoip enrichment
can take place until downloader is started with workaround (setting
`ingest.geoip.downloader.enabled` to `false` and `true` again). This is
because logic that was used to lower number of requests / cluster update
listeners at the startup was too optimistic about order of actions / who
can be elected master at what time.  This change fixes that and also
cleans up logs when there are some ignorable errors and adds debug
logging on start and stop of the task to ease up troubleshooting. It
also adds rolling upgrade test to make sure the fix works.