There is no way to disable refresh token revocation using configuration.
\League\OAuth2\Server\AuthorizationServer::revokeRefreshTokens
I'm actually forced to set the value using compiler pass and calling it before enableGrantType is called.
$authorizationServer = $container->getDefinition('League\OAuth2\Server\AuthorizationServer');
$calls = $authorizationServer->getMethodCalls();
array_unshift($calls, ['revokeRefreshTokens', [false]]);
$authorizationServer->setMethodCalls($calls);