[client] bound system info / posture-check gathering with a timeout to prevent sync-loop freeze (#6512)

* Wraps syestem info / posture checks into a goroutine with timeout

e.checks = checks is set before doing the SyncMeta,
so if it fails next time isCheckEquals compares true and bypasses
the update. This is to avoid another repeating the 15 seconds hang.
The checks will be synced on reconnect or posture checks changes
push from mgmt.

* Propagate context to OS calls that can leverage its cancellation / timeout

* Distinguish timeout from cancellation in logs

* Dont log twice

* Block on timeout failure and reapply the exclude_ips

* Refactor for complexity

client/system/process.go

@@ -3,24 +3,30 @@
 package system
 
 import (
+	"context"
 	"os"
 	"slices"
 
 	"github.com/shirou/gopsutil/v3/process"
 )
 
-// getRunningProcesses returns a list of running process paths.
-func getRunningProcesses() ([]string, error) {
-	processIDs, err := process.Pids()
+// getRunningProcesses returns a list of running process paths. The context bounds the work:
+// the per-PID loop bails as soon as ctx is done, and the gopsutil calls honor it where they
+// can, so a stuck enumeration cannot run unbounded.
+func getRunningProcesses(ctx context.Context) ([]string, error) {
+	processIDs, err := process.PidsWithContext(ctx)
 	if err != nil {
 		return nil, err
 	}
 
 	processMap := make(map[string]bool)
 	for _, pID := range processIDs {
+		if err := ctx.Err(); err != nil {
+			return nil, err
+		}
 		p := &process.Process{Pid: pID}
 
-		path, _ := p.Exe()
+		path, _ := p.ExeWithContext(ctx)
 		if path != "" {
 			processMap[path] = false
 		}
@@ -35,18 +41,21 @@ func getRunningProcesses() ([]string, error) {
 }
 
 // checkFileAndProcess checks if the file path exists and if a process is running at that path.
-func checkFileAndProcess(paths []string) ([]File, error) {
+func checkFileAndProcess(ctx context.Context, paths []string) ([]File, error) {
 	files := make([]File, len(paths))
 	if len(paths) == 0 {
 		return files, nil
 	}
 
-	runningProcesses, err := getRunningProcesses()
+	runningProcesses, err := getRunningProcesses(ctx)
 	if err != nil {
 		return nil, err
 	}
 
 	for i, path := range paths {
+		if err := ctx.Err(); err != nil {
+			return nil, err
+		}
 		file := File{Path: path}
 
 		_, err := os.Stat(path)