[Select-to-speak] Fix test and canonicalize Select-to-speak button name

Fixes SelectToSpeakMouseSelectionTest.SystemUI test, and updates tray
button name for Select-to-speak to canonical capitalization case [1].
Screenshot: http://screen/AhDvoMuayfmSzP5

[1] go/accessibility-settings-revamp-strings

Bug: None.
AX-Relnotes: N/A.
Change-Id: Iac3820020f7563d4ac9b5526739875083e473e34
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3995488
Auto-Submit: Josiah Krutz <josiahk@google.com>
Commit-Queue: Anastasia Helfinstein <anastasi@google.com>
Commit-Queue: Josiah Krutz <josiahk@google.com>
Reviewed-by: Anastasia Helfinstein <anastasi@google.com>
Cr-Commit-Position: refs/heads/main@{#1066690}

ash/ash_strings.grd

@@ -3013,7 +3013,7 @@ Connect your device to power.
         IME menu button
       </message>
       <message name="IDS_ASH_SELECT_TO_SPEAK_TRAY_ACCESSIBLE_NAME" desc="The accessible text for the select-to-speak menu icon in the status tray.">
-        Select-to-Speak button
+        Select-to-speak button
       </message>
       <message name="IDS_ASH_AUTOCLICK_TRAY_ACCESSIBLE_NAME" desc="The accessible text for the automatic clicks menu icon in the status tray.">
         Automatic clicks button

ash/ash_strings_grd/IDS_ASH_SELECT_TO_SPEAK_TRAY_ACCESSIBLE_NAME.png.sha1

@@ -0,0 +1 @@
+1184c16c08d46b87ecf556b255497b912bce2bc4

chrome/browser/resources/chromeos/accessibility/select_to_speak/select_to_speak_mouse_selection_test.js

@@ -330,7 +330,7 @@ AX_TEST_F('SelectToSpeakMouseSelectionTest', 'SystemUI', async function() {
       // Sometimes we get "Select-to-speak button" and sometimes
       // "Select-to-speak". Either is acceptable.
       this.assertEqualsCollapseWhitespace(
-          utterance.replace(/button/, ''), 'Select-to-speak');
+          utterance.replace(/button/, '').toLowerCase(), 'select-to-speak');
     })]);
 
     focusRingsCallback = this.newCallback((focusRings) => {