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/lock-rest-client.go

@@ -76,8 +76,8 @@ func (client *lockRESTClient) call(method string, values url.Values, body io.Rea
 	}
 
 	if isNetworkError(err) {
-		time.AfterFunc(defaultRetryUnit*3, func() {
-			// After 3 seconds, take this lock client online for a retry.
+		time.AfterFunc(defaultRetryUnit, func() {
+			// After 1 seconds, take this lock client online for a retry.
 			atomic.StoreInt32(&client.connected, 1)
 		})