Sort seed hosts to avoid unecessary configmap updates

[pebrc]

{"level":"info","@timestamp":"2019-11-25T01:27:00.726Z","logger":"settings","message":"Seed hosts updated","ver":"1.0.0-beta1-b559ec38","namespace":"e2e-m9cld-mercury","es_name":"test-es-keystore-drf6","hosts":["10.72.2.38:9300","10.72.1.31:9300","10.72.0.25:9300"]}
{"level":"info","@timestamp":"2019-11-25T01:27:00.781Z","logger":"zen2","message":"Ensuring no voting exclusions are set","ver":"1.0.0-beta1-b559ec38","namespace":"e2e-m9cld-mercury","es_name":"test-es-keystore-drf6"}
{"level":"info","@timestamp":"2019-11-25T01:27:00.849Z","logger":"elasticsearch-controller","message":"Updating status","ver":"1.0.0-beta1-b559ec38","iteration":1232,"namespace":"e2e-m9cld-mercury","es_name":"test-es-keystore-drf6"}
{"level":"info","@timestamp":"2019-11-25T01:27:00.849Z","logger":"elasticsearch-controller","message":"Ending reconciliation run","ver":"1.0.0-beta1-b559ec38","iteration":1232,"namespace":"e2e-m9cld-mercury","name":"test-es-keystore-drf6","took":0.8772917}
{"level":"info","@timestamp":"2019-11-25T01:27:00.849Z","logger":"elasticsearch-controller","message":"Starting reconciliation run","ver":"1.0.0-beta1-b559ec38","iteration":1233,"namespace":"e2e-m9cld-mercury","name":"test-es-keystore-drf6"}
{"level":"info","@timestamp":"2019-11-25T01:27:01.587Z","logger":"generic-reconciler","message":"Updating resource","ver":"1.0.0-beta1-b559ec38","kind":"ConfigMap","namespace":"e2e-m9cld-mercury","name":"test-es-keystore-drf6-es-unicast-hosts"}
{"level":"info","@timestamp":"2019-11-25T01:27:01.595Z","logger":"settings","message":"Seed hosts updated","ver":"1.0.0-beta1-b559ec38","namespace":"e2e-m9cld-mercury","es_name":"test-es-keystore-drf6","hosts":["10.72.1.31:9300","10.72.0.25:9300","10.72.2.38:9300"]}
{"level":"info","@timestamp":"2019-11-25T01:27:01.671Z","logger":"zen2","message":"Ensuring no voting exclusions are set","ver":"1.0.0-beta1-b559ec38","namespace":"e2e-m9cld-mercury","es_name":"test-es-keystore-drf6"}
{"level":"info","@timestamp":"2019-11-25T01:27:01.736Z","logger":"elasticsearch-controller","message":"Updating status","ver":"1.0.0-beta1-b559ec38","iteration":1233,"namespace":"e2e-m9cld-mercury","es_name":"test-es-keystore-drf6"}
{"level":"info","@timestamp":"2019-11-25T01:27:01.736Z","logger":"elasticsearch-controller","message":"Ending reconciliation run","ver":"1.0.0-beta1-b559ec38","iteration":1233,"namespace":"e2e-m9cld-mercury","name":"test-es-keystore-drf6","took":0.886652754}
{"level":"info","@timestamp":"2019-11-25T01:27:01.736Z","logger":"elasticsearch-controller","message":"Starting reconciliation run","ver":"1.0.0-beta1-b559ec38","iteration":1234,"namespace":"e2e-m9cld-mercury","name":"test-es-keystore-drf6"}
{"level":"info","@timestamp":"2019-11-25T01:27:02.466Z","logger":"generic-reconciler","message":"Updating resource","ver":"1.0.0-beta1-b559ec38","kind":"ConfigMap","namespace":"e2e-m9cld-mercury","name":"test-es-keystore-drf6-es-unicast-hosts"}
{"level":"info","@timestamp":"2019-11-25T01:27:02.475Z","logger":"settings","message":"Seed hosts updated","ver":"1.0.0-beta1-b559ec38","namespace":"e2e-m9cld-mercury","es_name":"test-es-keystore-drf6","hosts":["10.72.0.25:9300","10.72.2.38:9300","10.72.1.31:9300"]}

While trying to understand why our e2e tests fail I noticed a lot of seed host updates going on that seemed purely caused by non-deterministic pod order and consequently updates of the configmap we use for the unicast hosts file.

This PR sorts the seed nodes to avoid these configmap updates and adjusts the relevant unit test accordingly.

[thbkrkr]

LGTM

[sebgl]

good catch :)