Skip service discovery system-probe calls in cluster check runners (#54926)

### What does this PR do?

Stops the Agent from attempting to reach a local system-probe socket when running as a Cluster Checks Runner (CCR), caused by: #48000

Cluster Checks Runners are Deployment replicas, not DaemonSets, so they are never colocated with a system-probe on the same node and have no `hostPath` mount for its socket (`/opt/datadog-agent/run/sysprobe.sock`). Despite that, the workloadmeta process collector's service-discovery goroutine unconditionally queried system-probe's `/services` endpoint on CCR, which can never succeed there, and kept retrying on every collection interval, logging a `no such file or directory` error each time.

This PR adds a `helper.IsCLCRunner(...)` guard to `isServiceDiscoveryEnabled()` in `comp/core/workloadmeta/collectors/internal/process/process_collector.go`, so service discovery is treated as disabled on CCR regardless of the `discovery.enabled` system-probe config setting. This only gates the service-discovery goroutine and its system-probe calls; process collection, language detection, and GPU monitoring are unaffected.

There is no change in behavior for the node Agent or Cluster Agent. The guard is scoped to `helper.IsCLCRunner(...)`.

### Motivation

CONS-8502

Cluster Checks Runners have always attempted to query system-probe for service discovery on startup and on every collection interval, even though they're fundamentally incapable of reaching it (no local system-probe socket, since CCR isn't colocated per-node). This produces recurring `ERROR` logs about the missing socket, with no chance of ever succeeding.

### Describe how you validated your changes

- Added a unit test case in `TestStartConfiguration` (`process_collector_test.go`) verifying that `clc_runner_enabled: true` with `config_providers: [clusterchecks]` disables the collector even when `discovery.enabled: true`.
- Built a test image and deployed it as a real CCR pod in a cluster to reproduce and validate.

Co-authored-by: patrick.liang <patrick.liang@datadoghq.com>

Author: mrdoggopat

comp/core/workloadmeta/collectors/internal/process/BUILD.bazel

@@ -20,6 +20,7 @@ go_library(
             "//comp/core/telemetry/def",
             "//comp/core/telemetry/impl",
             "//comp/core/workloadmeta/def",
+            "//pkg/config/helper",
             "//pkg/config/model",
             "//pkg/discovery/core",
             "//pkg/discovery/language",
@@ -63,6 +64,7 @@ go_library(
             "//comp/core/telemetry/def",
             "//comp/core/telemetry/impl",
             "//comp/core/workloadmeta/def",
+            "//pkg/config/helper",
             "//pkg/config/model",
             "//pkg/discovery/core",
             "//pkg/discovery/language",

comp/core/workloadmeta/collectors/internal/process/process_collector.go

@@ -28,6 +28,7 @@ import (
 
 	"github.com/DataDog/datadog-agent/comp/core/config"
 	sysprobeconfig "github.com/DataDog/datadog-agent/comp/core/sysprobeconfig/def"
+	"github.com/DataDog/datadog-agent/pkg/config/helper"
 	pkgconfigmodel "github.com/DataDog/datadog-agent/pkg/config/model"
 	"github.com/DataDog/datadog-agent/pkg/languagedetection/languagemodels"
 	"github.com/DataDog/datadog-agent/pkg/process/procutil"
@@ -195,6 +196,14 @@ func (c *collector) isProcessCollectionEnabled() bool {
 
 // isServiceDiscoveryEnabled returns a boolean indicating if service discovery is enabled
 func (c *collector) isServiceDiscoveryEnabled() bool {
+	// Cluster Checks Runners are Deployment replicas, not DaemonSets, so they
+	// are never colocated with a system-probe on the same node and have no
+	// hostPath mount for its socket. Service discovery can never succeed
+	// there, so skip it entirely to avoid endlessly retrying system-probe
+	// requests and spamming "no such file or directory" error logs.
+	if helper.IsCLCRunner(c.config) {
+		return false
+	}
 	return serviceDiscoveryEnabled(c.systemProbeConfig)
 }
 

comp/core/workloadmeta/collectors/internal/process/process_collector_test.go

@@ -570,6 +570,18 @@ func TestStartConfiguration(t *testing.T) {
 			},
 			expectedError: errors.NewDisabled(componentName, "process collection, service discovery, language collection, and GPU monitoring are disabled"),
 		},
+		{
+			description: "service discovery enabled but disabled on CLC runner",
+			configOverrides: map[string]interface{}{
+				"process_config.process_collection.enabled": false,
+				"clc_runner_enabled":                        true,
+				"config_providers":                          []map[string]interface{}{{"name": "clusterchecks"}},
+			},
+			sysConfigOverrides: map[string]interface{}{
+				"discovery.enabled": true,
+			},
+			expectedError: errors.NewDisabled(componentName, "process collection, service discovery, language collection, and GPU monitoring are disabled"),
+		},
 	} {
 		t.Run(tc.description, func(t *testing.T) {
 			cfg := config.NewMock(t)