Changed font-weight to 400 to support light weight font (#8345)

* changed font-weight to 400 to support light weight font

* removed font-weight line and _CreateRoom.scss file

* removed _CreateRoom from _components.scss

Author: goelesha

res/css/_common.scss

@@ -294,7 +294,6 @@ legend {
     background-color: $background;
     color: $light-fg-color;
     z-index: 4012;
-    font-weight: 300;
     font-size: $font-15px;
     position: relative;
     padding: 24px;

res/css/_components.scss

@@ -27,7 +27,6 @@
 @import "./structures/_BackdropPanel.scss";
 @import "./structures/_CompatibilityPage.scss";
 @import "./structures/_ContextualMenu.scss";
-@import "./structures/_CreateRoom.scss";
 @import "./structures/_FileDropTarget.scss";
 @import "./structures/_FilePanel.scss";
 @import "./structures/_GenericErrorPage.scss";