config: fix grammar in helptip (#1986)

Requested by Graham87 at https://en.wikipedia.org/wiki/MediaWiki_talk:Gadget-Twinkle.js#Interface-protected_edit_request_on_28_July_2024

modules/twinkleconfig.js

@@ -218,7 +218,7 @@ Twinkle.config.sections = [
 			{
 				name: 'defaultToPartialBlocks',
 				label: 'Select partial blocks by default when opening the block menu',
-				helptip: 'If the user is already blocked, this will be overridden by in favor of defaulting to the current block type',
+				helptip: 'If the user is already blocked, this will be overridden in favor of defaulting to the current block type',
 				type: 'boolean'
 			},