valgrind : remove duplicate BCLog::Logger suppression

This was added in #17770, but is identical to the supression above.

Author: fanquake

contrib/valgrind.supp

@@ -184,11 +184,3 @@
    ...
    fun:_ZN5BCLog6Logger12StartLoggingEv
 }
-{
-   Suppress BCLog::Logger::StartLogging() still reachable memory warning
-   Memcheck:Leak
-   match-leak-kinds: reachable
-   fun:malloc
-   ...
-   fun:_ZN5BCLog6Logger12StartLoggingEv
-}