Update earpiece overlay button text for clarity (#3370)

* Update earpiece overlay button text for clarity

* update test snapshots

Author: toger5

locales/en/app.json

@@ -80,9 +80,9 @@
   },
   "disconnected_banner": "Connectivity to the server has been lost.",
   "earpiece": {
-    "overlay_back_button": "Back to video",
+    "overlay_back_button": "Back to Speaker Mode",
     "overlay_description": "Only works while using app",
-    "overlay_title": "Earpiece only mode"
+    "overlay_title": "Earpiece Mode"
   },
   "error": {
     "call_is_not_supported": "Call is not supported",

src/room/__snapshots__/InCallView.test.tsx.snap

@@ -109,7 +109,7 @@ exports[`InCallView > rendering > renders 1`] = `
       <h2
         class="_typography_6v6n8_153 _font-heading-md-semibold_6v6n8_112"
       >
-        Earpiece only mode
+        Earpiece Mode
       </h2>
       <p
         class="_typography_6v6n8_153 _font-body-md-regular_6v6n8_50"
@@ -123,7 +123,7 @@ exports[`InCallView > rendering > renders 1`] = `
         role="button"
         tabindex="0"
       >
-        Back to video
+        Back to Speaker Mode
       </button>
     </div>
     <div