[Android][TouchToFill] Use sentence case for buttons

Change title case buttons to sentence cases.

Bug: None
Change-Id: I670aa17ce81ab1fa7bebe3897af005ea7621f88e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1904066Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Commit-Queue: Friedrich [CET] <fhorschig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713770}

chrome/browser/touch_to_fill/android/internal/java/strings/android_touch_to_fill_strings.grd

@@ -126,10 +126,10 @@
         List of credentials to be filled on touch is closed.
       </message>
       <message name="IDS_MANAGE_PASSWORDS" desc="Title of the button at the end of a touch to fill sheet that will open the password preferences when tapped.">
-        Manage Passwords
+        Manage passwords
       </message>
       <message name="IDS_TOUCH_TO_FILL_CONFIRM" desc="Title of the button that confirms filling the only available set of credentials.">
-        Use Password
+        Use password
       </message>
     </messages>
   </release>