[QE] Improvements to KafkaConnect S2I BuildConfig and ImageStream configurations

Several improvements should be done to the KafkaConnectS2I BuildConfig and ImageStreams. In particular:

• Add a configuration for number of successful and failed builds to keep (for a start I suggest to hardcode 5 for both)

successfulBuildsHistoryLimit: 5
failedBuildsHistoryLimit: 5

• Use the `Local` ReferencePolicy in the ImageStreamsTag regardless of the insecureRegistry setting.