This commit applies the conventions that we documented on our wiki, see
https://github.com/spring-projects/spring-boot/wiki/GitHub-Actions.
In no particular order this:
* Use consistent single quotes for descriptions
* Order elements in a predictable order. In particular, inputs, outputs,
and environment variables are ordered alphabetically
Closes gh-42512
A full build requires a lot of disk space. I believe this is mostly
due to the large number of Docker images that the tests utilize. By
default, the amount of free disk space on an ubuntu-latest runner
does not meet or needs. In this commit, we work around this using
the free-disk-space action which deletes things like the Android
SDK and Haskell installations that are both large and not needed by
our builds.
Closes gh-40705
Andy Wilkinson
Stéphane Nicoll
Phillip Webb