Update package limit defaults

Plan limits were recently introduced for maximum package file sizes.

A production incident made it very clear that the initial default limits of 50MB were not correct for default.

The database defaults for

Maven: 3GB
NPM: 500MB
Conan: 3GB
NuGet: 500MB
PyPI: 3GB

should be updated before the 13.4 release to ensure the same breaking problems (inability to publish packages, specifically Maven), do not happen on self-managed instances when these plan limits are released in 13.4.