Remove unnecessary --min-split-size from aria2c downloader

This was added by another team member a long time ago, seemingly for the purposes of preventing a split on DASH/HLS segment files, as they would be already quite small.

However, just because they are small it isn't exactly a problem to have it split, and it would only split if the segment file size fits the default split size of 20M at least twice. I.e., if the segment is 45M, it will split twice. If the segment is 25M, it actually won't split at all. You may think 25M will split by 20M into two downloads, but actually the split size must explicitly fit for it to split. So for 2 downloads it will need to be 40MB in size, then 60, then 80, and so on.

A 40M or bigger segment file does in my opinion deserve to be split as it may genuinely reap speed benefits.

devine/core/downloaders/aria2c.py

@@ -60,7 +60,6 @@ async def aria2c(
         "-x", "16",  # The maximum number of connections to one server for each download
         "-j", "16",  # The maximum number of parallel downloads for every static (HTTP/FTP) URL
         "-s", ("1" if segmented else "16"),  # Download a file using N connections
-        "--min-split-size", ("1024M" if segmented else "20M"),  # effectively disable split if segmented
         "--allow-overwrite=true",
         "--auto-file-renaming=false",
         "--retry-wait", "2",  # Set the seconds to wait between retries.