DEV: Fix a composer state leak in tests

This is the one that made discourse-encrypt tests (and all subsequent tests) hang.

test/javascripts/acceptance/composer-actions-test.js

@@ -16,6 +16,9 @@ acceptance("Composer Actions", {
   },
   beforeEach() {
     _clearSnapshots();
+  },
+  afterEach() {
+    _clearSnapshots();
   }
 });
 
@@ -386,6 +389,9 @@ acceptance("Composer Actions With New Topic Draft", {
   },
   beforeEach() {
     _clearSnapshots();
+  },
+  afterEach() {
+    _clearSnapshots();
   }
 });