Fix helm shows "Not a table" issue when install Fission (#1387)

Helm treats the single line "extraCoreComponentPodConfig" in
values.yaml as a key value pair config.

```
extraCoreComponentPodConfig:
```

And when a user tries to install helm with providing config
like following, it failed.

```
extraCoreComponentPodConfig:
  nodeSelector:
    serverless: fission
```

The root cause is that helm treats config in default values.yaml
and providing config as two different types of config, which is
key-value vs. value table. And so it's unable for helm to merge these
two configs even with the same key name.

This PR comments out the single line config in default values.yaml
to prevent the issue.

charts/fission-all/values.yaml

@@ -181,7 +181,7 @@ persistence:
 ##               operator: In
 ##               values:
 ##                 - app
-extraCoreComponentPodConfig:
+#extraCoreComponentPodConfig:
 #  affinity:
 #  tolerations:
 #  nodeSelector:

charts/fission-core/values.yaml

@@ -125,7 +125,7 @@ persistence:
 ##               operator: In
 ##               values:
 ##                 - app
-extraCoreComponentPodConfig:
+#extraCoreComponentPodConfig:
 #  affinity:
 #  tolerations:
 #  nodeSelector: