renamed example_components to example-components and deleted old exampled

plugins/catalog-backend/fixtures/one_component.yaml

@@ -1,6 +0,0 @@
-apiVersion: backstage.io/v1beta1
-kind: Component
-metadata:
-  name: component3
-spec:
-  type: service

plugins/catalog-backend/fixtures/two_components.yaml

@@ -1,14 +0,0 @@
----
-apiVersion: backstage.io/v1beta1
-kind: Component
-metadata:
-  name: playlist-proxy
-spec:
-  type: service
----
-apiVersion: backstage.io/v1beta1
-kind: Component
-metadata:
-  name: artist-web
-spec:
-  type: website