Automatic merge from submit-queue (batch tested with PRs 40046, 40073, 40547, 40534, 40249)

Issue #13501 - printEvent Source to much more cleaner

Create a formatEventSource func and use it.



**What this PR does / why we need it**:
Adds a smarter way to print EventSource, removing "{ }" and the eventual extra ", " when Host is empty.
It was also reported in OpenShift issue https://github.com/openshift/origin/issues/6586

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #13501 

**Special notes for your reviewer**:
I have used this new func in all user facing printouts, but there are other places where EventSource are printed to logs, like DumpEventsInNamespace in test/e2e/framework/util.go for instance.
Don't know if I should correct there too...

**Release note**:

```release-note
Improve formatting of EventSource in kubectl get and kubectl describe
```