Condition transitions False->Progressing on reason/message change

[rfranzke]

How to categorize this PR?

/area ops-productivity
/kind enhancement
/priority normal

What this PR does / why we need it:
Failed conditions on Shoots do now transition from False status to Progressing in case the reason or message changes (if thresholds are defined in the gardenlet component config only, otherwise Progressing is not used anyways).
This will improve ops productivity as a condition will no longer stay False for a long time although different errors are happening subsequently.

Special notes for your reviewer:
/cc @timuthy

Release note:

Failed conditions on `Shoot`s do now transition from `False` status to `Progressing` in case the reason or message changes (if thresholds are defined in the gardenlet component config only, otherwise `Progressing` is not used anyways).

[timuthy]

/lgtm

[rfranzke]

Any further opinions?

[timebertt]

Hmm, TBH I'm not completely sure about the implications of this change.
I think, we need a bit more sophisticated logic here, unfortunately.
WDYT?

[timebertt]

/status author-action

[gardener-robot]

@rfranzke The pull request was assigned to you under author-action. Please unassign yourself when you are done. Thank you.

[rfranzke]

/unassign
/needs review

Incorporated feedback from @timebertt to only react on changes of the reason field (not message).

[timebertt]

Thanks
/lgtm