Revert "scripts/download: add sources CDN as first mirror"
This reverts commit c737a9ee6a9c47b6e553ac81bf293b1161e59799.
The source CDN has been discontinued in its current form and will take a
while to be reestablished. Even then it makes little sense to put a CDN
before other CDNs such as kernel.org, apache.org, sourceforge etc.
Signed-off-by: Jo-Philipp Wich <[email protected]>