Fix T100905: Official releases have the wrong branch in buildinfo

This is really old decision which should have been revisited as soon
as an overlapped release cycle was introduced.

The initial reasoning for such branch name override was to make it so
corrective releases have the same branch as the initial release when
we followed fully linear release cycle.

Nowadays such branch override is confusing and could even be misleading.

There are no add-ons using this property so it is very unlikely that
this is a breaking change.

build_files/cmake/buildinfo.cmake

@@ -103,10 +103,6 @@ if(EXISTS ${SOURCE_DIR}/.git)
       endif()
     endif()
 
-    if(MY_WC_BRANCH MATCHES "^blender-v")
-      set(MY_WC_BRANCH "master")
-    endif()
-
     unset(_git_below_check)
   endif()