Temporarily remove "final" from chart::FormattedString

...to check whether it has any effect on the strange Jenkins UBSan bot failures
that started with <https://ci.libreoffice.org/job/lo_ubsan/1253/>

Change-Id: I9e7c8c89d3347feb0d5d56f67ac3495553acfc3e

chart2/source/model/main/FormattedString.hxx

@@ -43,7 +43,7 @@ typedef ::cppu::WeakImplHelper<
     FormattedString_Base;
 }
 
-class FormattedString final :
+class FormattedString :
     public MutexContainer,
     public impl::FormattedString_Base,
     public ::property::OPropertySet