Don't limit the DownloadDiagnosisKeysTask to once a day (EXPOSUREAPP-3771) (#1616)

* Don't limit the DownloadDiagnosisKeysTask to once a day (EXPOSUREAPP-3771)

* Start DownloadDiagnosisKeysTask only once every hour (EXPOSUREAPP-3771)

* Fix initial state after fresh install (EXPOSUREAPP-3771)

* please ktlint and small fix

* Remove debug notification

* Use task state instead of a dedicated retrieving status indicator

* remove empty line

Co-authored-by: harambasicluka <64483219+harambasicluka@users.noreply.github.com>
Co-authored-by: Matthias Urhahn <matthias.urhahn@sap.com>