[Autofill Assistant] Remove redundant textColor.

Visually this doesn't change anything and makes autofill_assisant Chrome
UI style compliant.

Bug: 903508
Change-Id: I42cd48c8be5994aa2a3da877ba023a9228ad0eec
Reviewed-on: https://chromium-review.googlesource.com/c/1340160Reviewed-by: Theresa <twellington@chromium.org>
Commit-Queue: Mathias Carlen <mcarlen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608828}

chrome/android/java/res_autofill_assistant/layout/init_screen.xml

@@ -53,14 +53,12 @@
             android:paddingStart="50dp"/>
 
         <TextView
-            android:textColor="@color/default_text_color"
             android:layout_height="wrap_content"
             android:layout_width="wrap_content"
             android:textAppearance="@style/BlackTitle2"
             android:text="@string/autofill_assistant_onboarding_title" />
 
         <TextView
-            android:textColor="@color/default_text_color"
             android:layout_height="wrap_content"
             android:layout_width="wrap_content"
             android:paddingTop="40dp"