profiles/apparmor: IsLoaded: optimize

- Use a bufio.Scanner to read the profiles
- Use strings.Cut

Before/After:

    BenchmarkIsLoaded-10  2258	    508049 ns/op    244266 B/op    10004 allocs/op
    BenchmarkIsLoaded-10  5680	    208703 ns/op      4264 B/op	       4 allocs/op

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

profiles/apparmor/apparmor.go

@@ -103,20 +103,17 @@ func isLoaded(name string, fileName string) (bool, error) {
 	}
 	defer file.Close()
 
-	r := bufio.NewReader(file)
-	for {
-		p, err := r.ReadString('\n')
-		if err == io.EOF {
-			break
-		}
-		if err != nil {
-			return false, err
-		}
-		if strings.HasPrefix(p, name+" ") {
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		if prefix, _, ok := strings.Cut(scanner.Text(), " "); ok && prefix == name {
 			return true, nil
 		}
 	}
 
+	if err := scanner.Err(); err != nil {
+		return false, err
+	}
+
 	return false, nil
 }