[#1671] Use max builtin where possible

gopatcH:
```
@@
var d, a expression
@@
-if d < a {
-    d = a
-}
-return d
+return max(d, a)

@@
var d, a expression
@@
-if d <= a {
-    d = a
-}
-return d
+return max(d, a)
```

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

cmd/frostfs-node/config/engine/shard/boltdb/boltdb.go

@@ -37,10 +37,7 @@ func (x *Config) Perm() fs.FileMode {
 // Returns 0 if the value is not a positive number.
 func (x *Config) MaxBatchDelay() time.Duration {
 	d := config.DurationSafe((*config.Config)(x), "max_batch_delay")
-	if d < 0 {
-		d = 0
-	}
-	return d
+	return max(d, 0)
 }
 
 // MaxBatchSize returns the value of "max_batch_size" config parameter.
@@ -48,10 +45,7 @@ func (x *Config) MaxBatchDelay() time.Duration {
 // Returns 0 if the value is not a positive number.
 func (x *Config) MaxBatchSize() int {
 	s := int(config.IntSafe((*config.Config)(x), "max_batch_size"))
-	if s < 0 {
-		s = 0
-	}
-	return s
+	return max(s, 0)
 }
 
 // NoSync returns the value of "no_sync" config parameter.
@@ -66,8 +60,5 @@ func (x *Config) NoSync() bool {
 // Returns 0 if the value is not a positive number.
 func (x *Config) PageSize() int {
 	s := int(config.SizeInBytesSafe((*config.Config)(x), "page_size"))
-	if s < 0 {
-		s = 0
-	}
-	return s
+	return max(s, 0)
 }

cmd/frostfs-node/config/engine/shard/pilorama/config.go

@@ -52,10 +52,7 @@ func (x *Config) NoSync() bool {
 // Returns 0 if the value is not a positive number.
 func (x *Config) MaxBatchDelay() time.Duration {
 	d := config.DurationSafe((*config.Config)(x), "max_batch_delay")
-	if d <= 0 {
-		d = 0
-	}
-	return d
+	return max(d, 0)
 }
 
 // MaxBatchSize returns the value of "max_batch_size" config parameter.
@@ -63,8 +60,5 @@ func (x *Config) MaxBatchDelay() time.Duration {
 // Returns 0 if the value is not a positive number.
 func (x *Config) MaxBatchSize() int {
 	s := int(config.IntSafe((*config.Config)(x), "max_batch_size"))
-	if s <= 0 {
-		s = 0
-	}
-	return s
+	return max(s, 0)
 }