Batch uploads of large files behave strangely.

### Steps to reproduce

1. Prepare several files with sizes between 1.4 and 1.5 GB (based on the media maximum size of 1536 MB configured in the Synapse configuration file `homeserver.yaml`);
2. Drag these files in batches to the Web UI, and select "Upload All".

### Outcome

#### What did you expect?
n/a

#### What happened instead?
The upload speed becomes very slow, only about 150 Mbps in my case, and most of the selected files fail to upload. But the same files, manually uploaded one by one, behave normally. Under normal circumstances, the average upload speed of a large file is 950 Mbps in my case.

I guess the following events may have happened internally:
1. The application simultaneously initiated the same number of requests as the files to be uploaded;
2. These requests competed for bandwidth, and some progressed very slowly or even without any data passing, so that the transfer could not be resumed within 30 seconds, so these files were judged as failed uploads;
3. The remaining ones obtained enough bandwidth to continue to transfer until the upload was completed.

My suggestion for improvement is to let multiple files enter a queue when uploading, Upload one by one.
**This problem can be reproduced in both the browser and the desktop client.**

### Operating system

x64 Windows 11 (10.0.22631)

### Browser information

Cent Browser (Chromium 118)

### URL for webapp

Element Web 1.11.82

### Application version

Element Desktop 1.11.82 (x64)

### Homeserver

Synapse 1.117.0

### Will you send logs?

No