Docker informed us that for official multi-arch Docker builds, there
needs to be a single Dockerfile and build context that can be used for
each supported architecture. Therefore, rework the build to move the
relevant architecture logic into the Dockerfile, and merge the aarch64
/ x64 docker context builds.
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.