Update log keys to match logstream

This updates our log message formats to match the standard format used
in Knative, including by its logstream package.

This should prevent lots of logspam during tests.

config/config-logging.yaml

@@ -21,7 +21,6 @@ metadata:
     app.kubernetes.io/instance: default
     app.kubernetes.io/part-of: tekton-pipelines
 data:
-  # Common configuration for all knative codebase
   zap-logger-config: |
     {
       "level": "info",
@@ -34,11 +33,11 @@ data:
       "errorOutputPaths": ["stderr"],
       "encoding": "json",
       "encoderConfig": {
-        "timeKey": "ts",
-        "levelKey": "level",
+        "timeKey": "timestamp",
+        "levelKey": "severity",
         "nameKey": "logger",
         "callerKey": "caller",
-        "messageKey": "msg",
+        "messageKey": "message",
         "stacktraceKey": "stacktrace",
         "lineEnding": "",
         "levelEncoder": "",