[Merge] ~lamoura/update-notifier:show-only-esm-infra-alerts-on-esm-machine into update-notifier:master

[Lucas Albuquerque Medeiros de Moura]

Hi Brian, thanks for the review. About the SRU bug, yes we have one already for it:
https://bugs.launchpad.net/ubuntu/+source/update-notifier/+bug/1926990

I have also added the code to retry on calling lsb_release and I have added a new entry on changelog too
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https://code.launchpad.net/~lamoura/update-notifier/+git/update-notifier/+merge/402163
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