MM-55252 Update RHS Thread View to Use Relative Timestamps (#26605)

* switch RHS thread to relative time

* update snapshot

webapp/channels/src/components/rhs_thread/__snapshots__/rhs_thread.test.tsx.snap

@@ -33,7 +33,7 @@ exports[`components/RhsThread should match snapshot 1`] = `
     fromSuppressed={false}
     isThreadView={false}
     rootPostId="id"
-    useRelativeTimestamp={false}
+    useRelativeTimestamp={true}
   />
 </div>
 `;

webapp/channels/src/components/rhs_thread/rhs_thread.tsx

@@ -59,7 +59,7 @@ const RhsThread = ({
             />
             <ThreadViewer
                 rootPostId={selected.id}
-                useRelativeTimestamp={false}
+                useRelativeTimestamp={true}
                 isThreadView={false}
                 fromSuppressed={fromSuppressed}
             />