Merge bitcoin/bitcoin#27173: valgrind: remove libsecp256k1 suppression

29b62c0 valgrind: remove libsecp256k1 suppression (fanquake)

Pull request description:

  I am no-longer been able to recreate this issue, atleast after the most recent libsecp256k1 changes. Can someone else confirm?

ACKs for top commit:
  MarcoFalke:
    lgtm ACK 29b62c0
  sipa:
    utACK 29b62c0

Tree-SHA512: e61e5b88ac2af3c779f23d999938bec4497f6433a029c07dd57a9481fe9cc104d8d8f63586910b29f41e66bbf0ed094bc7539c0df84754a1783c4b1b15af072e

Author: fanquake

contrib/valgrind.supp

@@ -98,14 +98,6 @@
    fun:_Znwm
    fun:_Z11LogInstancev
 }
-{
-   Suppress secp256k1_context_create still reachable memory warning
-   Memcheck:Leak
-   match-leak-kinds: reachable
-   fun:malloc
-   ...
-   fun:secp256k1_context_create
-}
 {
    Suppress BCLog::Logger::StartLogging() still reachable memory warning
    Memcheck:Leak