[receivercreator] Validate endpoint's configuration before starting r…

…eceivers (open-telemetry#35416)

**Description:** 
The `receivercreator` should validate the runtime configurations before
starting a receiver. This PR adds this validation.

**Link to tracking Issue:** <Issue number if applicable> Fixes
open-telemetry#33145

**Testing:** 
Using the following helm chart's values:
```yaml
mode: daemonset

config:
  extensions:
    k8s_observer:
      auth_type: serviceAccount
      node: ${env:K8S_NODE_NAME}
      observe_nodes: true
  exporters:
    debug:
      verbosity: basic
  receivers:
    receiver_creator/3:
      watch_observers: [ k8s_observer ]
      receivers:
        apache:
          rule: type == "k8s.node"
          config:
            endpoint: "http://localhost:8080/server-status?manual"
  service:
    extensions: [health_check, k8s_observer]
    pipelines:
      metrics:
        receivers: [receiver_creator/3]
        processors: [batch]
        exporters: [debug]
```

Expect to see an error after the config's validation:

```console
2024-09-25T10:46:56.778Z	error	[email protected]/observerhandler.go:159	failed to start receiver	{"kind": "receiver", "name": "receiver_creator/3", "data_type": "metrics", "receiver": "apache", "error": "invalid runtime receiver config: receivers::apache: query must be 'auto': 'http://localhost:8080/server-status?manual'"}
github.com/open-telemetry/opentelemetry-collector-contrib/receiver/receivercreator.(*observerHandler).OnAdd
	github.com/open-telemetry/opentelemetry-collector-contrib/receiver/[email protected]/observerhandler.go:159
github.com/open-telemetry/opentelemetry-collector-contrib/extension/observer.(*EndpointsWatcher).updateAndNotifyOfEndpoints
	github.com/open-telemetry/opentelemetry-collector-contrib/extension/[email protected]/endpointswatcher.go:111
```

This stops the execution of the receiver which would lead to fetch
errors (as described in the respective issue
open-telemetry#33145):

```console
2024-05-21T09:17:46.749Z	error	[email protected]/scraper.go:67	failed to fetch Apache Httpd stats	{"kind": "receiver", "name": "receiver_creator/3", "data_type": "metrics", "name": "apache//receiver_creator/3{endpoint=\"http://localhost:8080/server-status?manual\"}/k8s_observer/kind-control-plane-b75cdcf9-ee9d-4cb8-aa53-1ceb030d898d", "error": "Get \"http://localhost:8080/server-status?manual\": dial tcp [::1]:8080: connect: connection refused"}
github.com/open-telemetry/opentelemetry-collector-contrib/receiver/apachereceiver.(*apacheScraper).scrape
	github.com/open-telemetry/opentelemetry-collector-contrib/receiver/[email protected]/scraper.go:67
go.opentelemetry.io/collector/receiver/scraperhelper.ScrapeFunc.Scrape
	go.opentelemetry.io/collector/[email protected]/scraperhelper/scraper.go:20
go.opentelemetry.io/collector/receiver/scraperhelper.(*controller).scrapeMetricsAndReport
	go.opentelemetry.io/collector/[email protected]/scraperhelper/scrapercontroller.go:194
go.opentelemetry.io/collector/receiver/scraperhelper.(*controller).startScraping.func1
	go.opentelemetry.io/collector/[email protected]/scraperhelper/scrapercontroller.go:169
2024-05-21T09:17:46.750Z	error	scraperhelper/scrapercontroller.go:197	Error scraping metrics	{"kind": "receiver", "name": "receiver_creator/3", "data_type": "metrics", "name": "apache//receiver_creator/3{endpoint=\"http://localhost:8080/server-status?manual\"}/k8s_observer/kind-control-plane-b75cdcf9-ee9d-4cb8-aa53-1ceb030d898d", "error": "Get \"http://localhost:8080/server-status?manual\": dial tcp [::1]:8080: connect: connection refused", "scraper": "apache"}
```

**Documentation:** <Describe the documentation added.>

Signed-off-by: ChrsMark <[email protected]>

.chloggen/add_receivercreator_config_validation.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: receivercreator
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Validate endpoint's configuration before starting receivers
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [33145]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

receiver/receivercreator/runner.go

@@ -137,6 +137,9 @@ func (run *receiverRunner) loadRuntimeReceiverConfig(
 	if err := mergedConfig.Unmarshal(receiverCfg); err != nil {
 		return nil, "", fmt.Errorf("failed to load %q template config: %w", receiver.id.String(), err)
 	}
+	if err := component.ValidateConfig(receiverCfg); err != nil {
+		return nil, "", fmt.Errorf("invalid runtime receiver config: receivers::%s: %w", receiver.id, err)
+	}
 	return receiverCfg, targetEndpoint, nil
 }