[chore] [receiver/hostmetrics] Remove any references to uptimescraper (open-telemetry#40093)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description
I renamed this scraper to `system`, but neglected to remove a number of
references to the old `uptimescraper` name. While I was here, I also
cleaned up some OS support problems where there wasn't proper guarding,
but it never showed up cause it's supported on the 3 OS's we run tests
on.

<!-- Issue number (e.g. #1234) or full URL to issue, if applicable. -->
#### Link to tracking issue
Fixes open-telemetry#40092

<!--Describe what testing was performed and which tests were added.-->
#### Testing
Locally ran all tests and integration tests.

Author: braydonk

receiver/hostmetricsreceiver/internal/scraper/systemscraper/config.go

@@ -7,7 +7,7 @@ import (
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/systemscraper/internal/metadata"
 )
 
-// Config relating to Uptime Metric Scraper.
+// Config relating to System Metric Scraper.
 type Config struct {
 	// MetricsBuilderConfig allows to customize scraped metrics/attributes representation.
 	metadata.MetricsBuilderConfig `mapstructure:",squash"`

receiver/hostmetricsreceiver/internal/scraper/systemscraper/factory.go

@@ -14,6 +14,11 @@ import (
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/systemscraper/internal/metadata"
 )
 
+var (
+	supportedOS      = runtime.GOOS == "linux" || runtime.GOOS == "windows" || runtime.GOOS == "darwin"
+	errUnsupportedOS = errors.New("the system scraper is only available on Linux, Windows, or macOS")
+)
+
 // NewFactory for System scraper.
 func NewFactory() scraper.Factory {
 	return scraper.NewFactory(metadata.Type, createDefaultConfig, scraper.WithMetrics(createMetricsScraper, metadata.MetricsStability))
@@ -32,14 +37,14 @@ func createMetricsScraper(
 	settings scraper.Settings,
 	cfg component.Config,
 ) (scraper.Metrics, error) {
-	if runtime.GOOS != "linux" && runtime.GOOS != "windows" && runtime.GOOS != "darwin" {
-		return nil, errors.New("uptime scraper only available on Linux, Windows, or macOS")
+	if !supportedOS {
+		return nil, errUnsupportedOS
 	}
 
-	uptimeScraper := newUptimeScraper(ctx, settings, cfg.(*Config))
+	systemScraper := newSystemScraper(ctx, settings, cfg.(*Config))
 
 	return scraper.NewMetrics(
-		uptimeScraper.scrape,
-		scraper.WithStart(uptimeScraper.start),
+		systemScraper.scrape,
+		scraper.WithStart(systemScraper.start),
 	)
 }

receiver/hostmetricsreceiver/internal/scraper/systemscraper/factory_test.go

@@ -19,6 +19,11 @@ func TestCreateSystemScraper(t *testing.T) {
 
 	scraper, err := factory.CreateMetrics(context.Background(), scrapertest.NewNopSettings(metadata.Type), cfg)
 
-	assert.NoError(t, err)
-	assert.NotNil(t, scraper)
+	if supportedOS {
+		assert.NoError(t, err)
+		assert.NotNil(t, scraper)
+	} else {
+		assert.ErrorIs(t, err, errUnsupportedOS)
+		assert.Nil(t, scraper)
+	}
 }

receiver/hostmetricsreceiver/internal/scraper/systemscraper/system_scraper.go

@@ -16,7 +16,7 @@ import (
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/systemscraper/internal/metadata"
 )
 
-// scraper for Uptime Metrics
+// scraper for System Metrics
 type systemsScraper struct {
 	settings scraper.Settings
 	config   *Config
@@ -27,8 +27,8 @@ type systemsScraper struct {
 	uptime   func(context.Context) (uint64, error)
 }
 
-// newUptimeScraper creates an Uptime related metric
-func newUptimeScraper(_ context.Context, settings scraper.Settings, cfg *Config) *systemsScraper {
+// newSystemScraper creates an Uptime related metric
+func newSystemScraper(_ context.Context, settings scraper.Settings, cfg *Config) *systemsScraper {
 	return &systemsScraper{settings: settings, config: cfg, bootTime: host.BootTimeWithContext, uptime: host.UptimeWithContext}
 }
 

receiver/hostmetricsreceiver/internal/scraper/systemscraper/system_scraper_test.go

@@ -18,10 +18,14 @@ import (
 )
 
 func TestScrape(t *testing.T) {
+	if !supportedOS {
+		t.Skip()
+	}
+
 	ctx := context.Background()
 	fakeDate := time.Date(2006, 0o1, 0o2, 0o3, 0o4, 0o5, 0, time.UTC)
 
-	s := newUptimeScraper(ctx, scrapertest.NewNopSettings(metadata.Type), &Config{
+	s := newSystemScraper(ctx, scrapertest.NewNopSettings(metadata.Type), &Config{
 		MetricsBuilderConfig: metadata.DefaultMetricsBuilderConfig(),
 	})