[Backport release-1.1] Fix: observability installation (#2735)

* fix observability installation

(cherry picked from commit 32646ea3b6)

* fix nil pointer

(cherry picked from commit 29564fe264)

* fix nil pointer

(cherry picked from commit 716d869dc5)

* remove asset, build in trait

(cherry picked from commit acbeeb16e1)

Co-authored-by: qiaozp <chivalry.pp@gmail.com>

docs/examples/obervability/README.md

@@ -1,4 +1,4 @@
 This repo is the source artifacts for addon `observability`.
 
-- All .cue files are source artifacts from definition of [observability-asset](../../../vela-templates/addons/observability-asset).
-- `initializer-observability.yaml` will help developer  [observability](../../../vela-templates/addons/observability).
+- All files in definitions are source artifacts which is now built-in in `vela-core` helm chart.
+- `application-observability.yaml` will help developer  [observability](../../../vela-templates/addons/observability).

docs/examples/obervability/trait-import-grafana-dashboard.cue

@@ -1,21 +0,0 @@
-outputs: registerdatasource: {
-	apiVersion: "grafana.extension.oam.dev/v1alpha1"
-	kind:       "ImportDashboard"
-	spec: {
-		grafana: {
-			service:                   parameter.grafanaServiceName
-			namespace:                 parameter.grafanaServiceNamespace
-			credentialSecret:          parameter.credentialSecret
-			credentialSecretNamespace: parameter.credentialSecretNamespace
-		}
-		urls: parameter.urls
-	}
-}
-
-parameter: {
-	grafanaServiceName:        string
-	grafanaServiceNamespace:   *"default" | string
-	credentialSecret:          string
-	credentialSecretNamespace: *"default" | string
-	urls: [...string]
-}

docs/examples/obervability/trait-register-grafana-datasource.cue

@@ -1,31 +0,0 @@
-outputs: registerdatasource: {
-	apiVersion: "grafana.extension.oam.dev/v1alpha1"
-	kind:       "DatasourceRegistration"
-	spec: {
-		grafana: {
-			service:                   parameter.grafanaServiceName
-			namespace:                 parameter.grafanaServiceNamespace
-			credentialSecret:          parameter.credentialSecret
-			credentialSecretNamespace: parameter.credentialSecretNamespace
-		}
-		datasource: {
-			name:      parameter.name
-			type:      parameter.type
-			access:    parameter.access
-			service:   parameter.service
-			namespace: parameter.namespace
-		}
-	}
-}
-
-parameter: {
-	grafanaServiceName:        string
-	grafanaServiceNamespace:   *"default" | string
-	credentialSecret:          string
-	credentialSecretNamespace: string
-	name:                      string
-	type:                      string
-	access:                    *"proxy" | string
-	service:                   string
-	namespace:                 *"default" | string
-}