I18n: Improve translators comments [3].

* Add missing translators comments.
* Fix placement of some translators comments.
  Translators comments should be on the line directly above the line containing the translation function call for optimal compatibility with various `.pot` file generation tools.
  The CS auto-fixing, which changed some inconsistent function calls to multi-line function calls, is part of the reason why this was no longer the case for a select group of translators comments.

Includes minor code layout fixes.

Patch `44360-wp-admin-includes-dir.patch` of the series.

Props flipkeijzer, alvarogois, michielatyoast
See #44360

Built from https://develop.svn.wordpress.org/trunk@43598


git-svn-id: http://core.svn.wordpress.org/trunk@43427 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-language-pack-upgrader.php

@@ -343,8 +343,8 @@ class Language_Pack_Upgrader extends WP_Upgrader {
 			return new WP_Error(
 				'incompatible_archive_pomo',
 				$this->strings['incompatible_archive'],
-				/* translators: 1: .po, 2: .mo */
 				sprintf(
+					/* translators: 1: .po, 2: .mo */
 					__( 'The language pack is missing either the %1$s or %2$s files.' ),
 					'<code>.po</code>',
 					'<code>.mo</code>'