Backport of #48849. Update `.editorconfig` to make the Java settings the
default for all files, and then apply a 2-space indent to all `*.gradle`
files. Then reformat all the files.
Testclusters currently provides protection from clusters living past the
life of a build by adding a shutdown hook to java. While this works in
some cases, it does not cover all cases like where the daemon is killed
with SIGKILL.
To handle these other cases, this commit replaces the shutdown hooks with
a separate process (one per build) that manages reaping external services
if gradle dies.
Rene Groeschke
Rory Hunter
Mark Vieira
Ryan Ernst