Revise strings for Assistant preferred input.

Screenshot in the bug.

Bug: b:119662514
Change-Id: Iee19fd5f23942fd13ed03ff61b804db04f36f66d
Reviewed-on: https://chromium-review.googlesource.com/c/1340959Reviewed-by: Ken Rockot <rockot@google.com>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Commit-Queue: David Black <dmblack@google.com>
Cr-Commit-Position: refs/heads/master@{#609070}

chrome/app/settings_strings.grdp

@@ -2729,10 +2729,10 @@
     Allow the Assistant to show you notifications
   </message>
   <message name="IDS_SETTINGS_GOOGLE_ASSISTANT_LAUNCH_WITH_MIC_OPEN" desc="Title for a toggle that determines whether to open the microphone when launching the Assistant.">
-    Voice activation
+    Preferred input
   </message>
   <message name="IDS_SETTINGS_GOOGLE_ASSISTANT_LAUNCH_WITH_MIC_OPEN_DESCRIPTION" desc="Sub label for launch-with-microphone-open toggle.">
-    Use speech instead of keyboard when you start your Assistant
+    Default to using voice instead of keyboard
   </message>
   <message name="IDS_SETTINGS_GOOGLE_ASSISTANT_SETTINGS" desc="Title for a button that opens the Google Assistant app settings.">
     Google Assistant settings