chore: revert cs-fixer and fix a few styles

[bshaffer]

• addresses phpunit errors on PHP 7.3 (see PHPUnit 8.5.27 does not work on PHP 7.2.0-7.2.18 and PHP 7.3.0-7.3.5 sebastianbergmann/phpunit#5016)
• Pin php-cs-fixer to v3.8.0 because v3.9 broke several things for us.
• Fix a few cs problems that the later version actually caught

[snippet-bot]

Here is the summary of changes.

You are about to add 1 region tag.

• video/src/analyze_object_tracking_file.php:21, tag video_object_tracking

You are about to delete 1 region tag.

• video/src/analyze_object_tracking_file.php:21, tag video_object_tracking

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