Use injected Lookup service; remove deprecated method

The only production user of the deprecated
Hooks::isDisambiguationPage() method is the RelatedArticles extension;
the 'depends-on' patch here tweaks it to use the DisambiguatorLookup
service instead.

A similar patch to fix up a 3rd-party extension is at:
femiwiki/UnifiedExtensionForFemiwiki#139

This continues the slow cleanup moving to injected services from
globals.

Depends-On: Id2a10f2f1be0e38ddb8ebef5d5babb3daac3ce9a
Change-Id: I7f74c0c6347e7c5fea10c49aef665558762711d0

includes/Hooks.php

@@ -141,21 +141,6 @@ public function onRandomPageQuery( &$tables, &$conds, &$joinConds ) {
 		self::excludeDisambiguationPages( $tables, $conds, $joinConds );
 	}
 
-	/**
-	 * Convenience function for testing whether or not a page is a disambiguation page
-	 *
-	 * @deprecated Use DisambiguatorLookup service
-	 *
-	 * @param Title $title object of a page
-	 * @param bool $includeRedirects Whether to consider redirects to disambiguations as
-	 *   disambiguations.
-	 * @return bool
-	 */
-	public static function isDisambiguationPage( Title $title, $includeRedirects = true ) {
-		return MediaWikiServices::getInstance()->getService( 'DisambiguatorLookup' )
-			->isDisambiguationPage( $title, $includeRedirects );
-	}
-
 	/**
 	 * Add 'mw-disambig' CSS class to links to disambiguation pages.
 	 * @param array $pageIdToDbKey Prefixed DB keys of the pages linked to, indexed by page_id
@@ -168,8 +153,9 @@ public function onGetLinkColours( $pageIdToDbKey, &$colours, $title ) {
 			return;
 		}
 
-		$pageIds = MediaWikiServices::getInstance()->getService( 'DisambiguatorLookup' )
-			->filterDisambiguationPageIds( array_keys( $pageIdToDbKey ) );
+		$pageIds = $this->lookup->filterDisambiguationPageIds(
+			array_keys( $pageIdToDbKey )
+		);
 
 		foreach ( $pageIds as $pageId ) {
 			if ( isset( $colours[ $pageIdToDbKey[$pageId] ] ) ) {