Screenshots is shipping browser test files as part of the Firefox build

[Standard8]

In the generated section of screenshot's moz.build, various test files are being set as FINAL_TARGET_FILES. This means they're being including in the xpi that is shipped with Firefox itself.

These shouldn't be necessary as the build system automatically bundles up test files separately to Firefox itself.

Additionally, the .eslintrc.yml isn't actually being shipped, I suspect because it is a dot file the build system is ignoring it somehow.

https://searchfox.org/mozilla-central/rev/adcc169dcf58c2e45ba65c4ed5661d666fc3ac74/browser/extensions/screenshots/moz.build#463-467

FINAL_TARGET_FILES.features['screenshots@mozilla.org']["test"]["browser"] += [
  'test/browser/.eslintrc.yml',
  'test/browser/browser.ini',
  'test/browser/browser_screenshots_ui_check.js'
]