[receiver/hostmetrics] Mark hostmetrics.process.onWindowsUseNewGetProcesses feature gate as stable (#40420)

#### Description
Mark `hostmetrics.process.onWindowsUseNewGetProcesses` feature gate as
stable

#### Link to tracking issue
Follow-up to PR #38589

Author: pjanotti

.chloggen/mark-onWindowsUseNewGetProcesses-gate-to-stable.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: deprecation
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: receiver/hostmetrics
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Mark `hostmetrics.process.onWindowsUseNewGetProcesses` feature gate as stable
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [32947]
+
+# (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: [user]

receiver/hostmetricsreceiver/internal/scraper/processscraper/get_process_handles_windows.go

@@ -15,17 +15,15 @@ import (
 	"golang.org/x/sys/windows"
 )
 
-var useNewGetProcessHandles = featuregate.GlobalRegistry().MustRegister(
+var _ = featuregate.GlobalRegistry().MustRegister(
 	"hostmetrics.process.onWindowsUseNewGetProcesses",
-	featuregate.StageBeta,
+	featuregate.StageStable,
 	featuregate.WithRegisterDescription("If disabled, the scraper will use the legacy implementation to retrieve process handles."),
+	featuregate.WithRegisterFromVersion("v0.123.0"),
+	featuregate.WithRegisterToVersion("v0.127.0"),
 )
 
 func getGopsutilProcessHandles(ctx context.Context) (processHandles, error) {
-	if !useNewGetProcessHandles.IsEnabled() {
-		return getGopsutilProcessHandlesLegacy(ctx)
-	}
-
 	snap, err := windows.CreateToolhelp32Snapshot(windows.TH32CS_SNAPPROCESS, 0)
 	if err != nil {
 		return nil, fmt.Errorf("could not create snapshot: %w", err)
@@ -67,18 +65,3 @@ func getGopsutilProcessHandles(ctx context.Context) (processHandles, error) {
 
 	return &gopsProcessHandles{handles: wrappedProcesses}, nil
 }
-
-func getGopsutilProcessHandlesLegacy(ctx context.Context) (processHandles, error) {
-	processes, err := process.ProcessesWithContext(ctx)
-	if err != nil {
-		return nil, err
-	}
-	wrapped := make([]wrappedProcessHandle, len(processes))
-	for i, p := range processes {
-		wrapped[i] = wrappedProcessHandle{
-			Process: p,
-		}
-	}
-
-	return &gopsProcessHandles{handles: wrapped}, nil
-}