[css-text] Make normal the initial value of text-spacing-trim

Part of #9511

Author: frivoal

css-text-4/Overview.bs

@@ -10430,7 +10430,7 @@ CJK Punctuation Spacing: the 'text-spacing-trim' property</h3>
 	<pre class="propdef">
 	Name: text-spacing-trim
 	Value: <<spacing-trim>> | auto
-	Initial: space-first
+	Initial: normal
 	Applies to: text
 	Inherited: yes
 	Percentages: N/A