Downloading dependencies for a Vaadin project takes unreasonably long #8716
Description
Describe the bug
The PR validation build for start.vaadin.com fails because it is unable to download dependencies for a new project within 30 minutes. This is not reasonable.
It seems to be caused by rate limiting on maven.vaadin.com. After a short while, requests to maven.vaadin.com start taking minutes before returning 404.
In the starter projects, there was only a maven.vaadin.com repository defined, which causes Maven to FIRST check that one for each dependency and then consult Maven central. This triggers the rate limit quite quickly and completely destroys the downloading performance.
As a workaround, the starters now explicitly specify Maven central first, and the dependency resolution that did not finish in 30 minutes takes 4 minutes
Expected-behavior
There is no aggressive rate limiting for downloading dependencies - which is the sole reason the repositories exist
Reproduction
git clone git@github.com:vaadin/skeleton-starter-flow-spring.git
cd skeleton-starter-flow-spring
git checkout 39f7ea83d3bbf84c5bebcbc95997a42dcd64b15e
mvn dependency:go-offline