testing: fix Kibana healthcheck (elastic#20683)

* testing: fix Kibana healthcheck

With elastic/kibana#74656,
Kibana images will no longer have Python installed.
Instead of parsing the result, just look for the
string "Looking good", which indicates Kibana is
healthy.

testing/environments/snapshot-oss.yml

@@ -27,7 +27,7 @@ services:
   kibana:
     image: docker.elastic.co/kibana/kibana-oss:8.0.0-SNAPSHOT
     healthcheck:
-      test: ["CMD-SHELL", 'python -c ''import urllib, json; response = urllib.urlopen("http://localhost:5601/api/status"); data = json.loads(response.read()); exit(1) if data["status"]["overall"]["state"] != "green" else exit(0);''']
+      test: ["CMD-SHELL", "curl -s http://localhost:5601/api/status | grep -q 'Looking good'"]
       retries: 600
       interval: 1s
 

testing/environments/snapshot.yml

@@ -29,6 +29,6 @@ services:
   kibana:
     image: docker.elastic.co/kibana/kibana:8.0.0-SNAPSHOT
     healthcheck:
-      test: ["CMD-SHELL", 'python -c ''import urllib, json; response = urllib.urlopen("http://localhost:5601/api/status"); data = json.loads(response.read()); exit(1) if data["status"]["overall"]["state"] != "green" else exit(0);''']
+      test: ["CMD-SHELL", "curl -s http://localhost:5601/api/status | grep -q 'Looking good'"]
       retries: 600
       interval: 1s

x-pack/libbeat/docker-compose.yml

@@ -50,7 +50,7 @@ services:
       file: ${ES_BEATS}/testing/environments/${TESTING_ENVIRONMENT}.yml
       service: kibana
     healthcheck:
-      test: ["CMD-SHELL", 'python -c ''import urllib, json; response = urllib.urlopen("http://myelastic:changeme@localhost:5601/api/status"); data = json.loads(response.read()); exit(1) if data["status"]["overall"]["state"] != "green" else exit(0);''']
+      test: ["CMD-SHELL", "curl -u myelastic:changeme -f http://localhost:5601/api/status | grep -q 'Looking good'"]
       retries: 1200
       interval: 5s
       start_period: 60s