Fix server-side demos with maps in folders

When maps are loaded from folders on the server, the same folders were used for demos but recording would usually fail due to the folders not existing in the demos folder.

Furthermore, the map name being written in the demo header also included the folder names, which causes the client to not find the map unless it also exists at that location.

Closes ddnet#9033.

src/engine/server/server.cpp

@@ -3393,13 +3393,13 @@ void CServer::DemoRecorder_HandleAutoStart()
 		char aTimestamp[20];
 		str_timestamp(aTimestamp, sizeof(aTimestamp));
 		char aFilename[IO_MAX_PATH_LENGTH];
-		str_format(aFilename, sizeof(aFilename), "demos/auto/server/%s_%s.demo", m_aCurrentMap, aTimestamp);
+		str_format(aFilename, sizeof(aFilename), "demos/auto/server/%s_%s.demo", GetMapName(), aTimestamp);
 		m_aDemoRecorder[RECORDER_AUTO].Start(
 			Storage(),
 			m_pConsole,
 			aFilename,
 			GameServer()->NetVersion(),
-			m_aCurrentMap,
+			GetMapName(),
 			m_aCurrentMapSha256[MAP_TYPE_SIX],
 			m_aCurrentMapCrc[MAP_TYPE_SIX],
 			"server",
@@ -3423,7 +3423,7 @@ void CServer::SaveDemo(int ClientId, float Time)
 	if(IsRecording(ClientId))
 	{
 		char aNewFilename[IO_MAX_PATH_LENGTH];
-		str_format(aNewFilename, sizeof(aNewFilename), "demos/%s_%s_%05.2f.demo", m_aCurrentMap, m_aClients[ClientId].m_aName, Time);
+		str_format(aNewFilename, sizeof(aNewFilename), "demos/%s_%s_%05.2f.demo", GetMapName(), m_aClients[ClientId].m_aName, Time);
 		m_aDemoRecorder[ClientId].Stop(IDemoRecorder::EStopMode::KEEP_FILE, aNewFilename);
 	}
 }
@@ -3433,13 +3433,13 @@ void CServer::StartRecord(int ClientId)
 	if(Config()->m_SvPlayerDemoRecord)
 	{
 		char aFilename[IO_MAX_PATH_LENGTH];
-		str_format(aFilename, sizeof(aFilename), "demos/%s_%d_%d_tmp.demo", m_aCurrentMap, m_NetServer.Address().port, ClientId);
+		str_format(aFilename, sizeof(aFilename), "demos/%s_%d_%d_tmp.demo", GetMapName(), m_NetServer.Address().port, ClientId);
 		m_aDemoRecorder[ClientId].Start(
 			Storage(),
 			Console(),
 			aFilename,
 			GameServer()->NetVersion(),
-			m_aCurrentMap,
+			GetMapName(),
 			m_aCurrentMapSha256[MAP_TYPE_SIX],
 			m_aCurrentMapCrc[MAP_TYPE_SIX],
 			"server",
@@ -3501,7 +3501,7 @@ void CServer::ConRecord(IConsole::IResult *pResult, void *pUser)
 		pServer->Console(),
 		aFilename,
 		pServer->GameServer()->NetVersion(),
-		pServer->m_aCurrentMap,
+		pServer->GetMapName(),
 		pServer->m_aCurrentMapSha256[MAP_TYPE_SIX],
 		pServer->m_aCurrentMapCrc[MAP_TYPE_SIX],
 		"server",