lock: improve locker initialization at init (#8776)

Use reference format to initialize lockers
during startup, also handle `nil` for NetLocker
in dsync and remove *errorLocker* implementation

Add further tuning parameters such as

 - DialTimeout is now 15 seconds from 30 seconds
 - KeepAliveTimeout is not 20 seconds, 5 seconds
   more than default 15 seconds
 - ResponseHeaderTimeout to 10 seconds
 - ExpectContinueTimeout is reduced to 3 seconds
 - DualStack is enabled by default remove setting
   it to `true`
 - Reduce IdleConnTimeout to 30 seconds from
   1 minute to avoid idleConn build up

Fixes #8773

cmd/posix.go

@@ -554,7 +554,9 @@ func (s *posix) SetDiskID(id string) {
 func (s *posix) MakeVolBulk(volumes ...string) (err error) {
 	for _, volume := range volumes {
 		if err = s.MakeVol(volume); err != nil {
-			return err
+			if err != errVolumeExists {
+				return err
+			}
 		}
 	}
 	return nil