Handle resource conflict while updating status in association reconciler

[thbkrkr]

This commit removes reconciliation errors that occur when the association controller updats the association's parent resource:

2022-02-07T10:24:27.808+0100    ERROR   manager.eck-operator.controller.beat-kibana-association-controller  
  Reconciler error {
    "service.version": "2.1.0-SNAPSHOT+48044437",
    "name": "filebeat",
    "namespace": "default",
    "error": "Operation cannot be fulfilled on beats.beat.k8s.elastic.co \"filebeat\": the object has been modified; 
              please apply your changes to the latest version and try again"
}

Similar to #824.

[barkbay]

@miriam-eid I think this is the fix for #4897

[thbkrkr]

@barkbay This silences errors coming from the xx-yy-association-controller, not the beat-controller, so #4897 still seems relevant.

[barkbay]

#4897 still seems relevant

While working on #4897 we (with @miriam-eid ) discovered that *beat-controller errors were actually already fixed (I can't remember in which pr/release). However, there were still some errors from *-association-controller which are now fixed.