cherry-pick: 4437 depr memory opt

Merge in DNS/adguard-home from 4437-rm-mem-opt to master

Updates #4437.
Updates #2044.

Squashed commit of the following:

commit d1e5520213f6b68570d18a8d831d4923112901ba
Merge: 73a6b494 8bb95469
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed Apr 6 19:37:09 2022 +0300

    Merge branch 'master' into 4437-rm-mem-opt

commit 73a6b4948cb32f1cb79a54b244018b29382fad76
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed Apr 6 18:33:23 2022 +0300

    all: imp log of changes

commit a62efcdcd44de300726c906c7f6198c0a02d4ccf
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed Apr 6 18:27:42 2022 +0300

    home: depr memory opt

internal/home/options.go

@@ -7,6 +7,7 @@ import (
 	"strconv"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/version"
+	"github.com/AdguardTeam/golibs/log"
 )
 
 // options passed from command-line arguments
@@ -27,10 +28,6 @@ type options struct {
 	// runningAsService flag is set to true when options are passed from the service runner
 	runningAsService bool
 
-	// disableMemoryOptimization - disables memory optimization hacks
-	// see memoryUsage() function for the details
-	disableMemoryOptimization bool
-
 	glinetMode bool // Activate GL-Inet compatibility mode
 
 	// noEtcHosts flag should be provided when /etc/hosts file shouldn't be
@@ -180,8 +177,12 @@ var noCheckUpdateArg = arg{
 var disableMemoryOptimizationArg = arg{
 	"Disable memory optimization.",
 	"no-mem-optimization", "",
-	nil, func(o options) (options, error) { o.disableMemoryOptimization = true; return o, nil }, nil,
-	func(o options) []string { return boolSliceOrNil(o.disableMemoryOptimization) },
+	nil, nil, func(_ options, _ string) (f effect, err error) {
+		log.Info("warning: using --no-mem-optimization flag has no effect and is deprecated")
+
+		return nil, nil
+	},
+	func(o options) []string { return nil },
 }
 
 var verboseArg = arg{