Quote string context only needs to escape double-quotes.

Escaping other things (such as braces) breaks other features (such
as text variables).

Fixes https://gitlab.com/kicad/code/kicad/issues/6973

common/string.cpp

@@ -102,9 +102,7 @@ wxString EscapeString( const wxString& aSource, ESCAPE_CONTEXT aContext )
         }
         else if( aContext == CTX_QUOTED_STR )
         {
-            if( c == '{' )
-                converted += "{brace}";
-            else if( c == '\"' )
+            if( c == '\"' )
                 converted += "{dblquote}";
             else
                 converted += c;