Corrects uses of setup as a verb to 'set up', leaves noun/noun-phrase
forms of setup as 'setup'. Also settles on 'teardown' as opposed to
tear-down for consistency across the codebase.

A few other minor comment/wording corrections.

This shouldn't result in any logical changes. I've done a quick smoke
test by building a local Android engine and running Flutter gallery, no
compile errors or other obvious issues.

Applied by running `/ci/format.sh | patch -p0` with the altered script
added in flutter/engine#16500. I did locally modify the script slightly
further so it would run against all Java files in the repo instead of
just modified ones.

Mainly improvements to javadoc and error logging. A bit of refactoring.

This reverts commit afb206d3.