Revert "Add valgrind suppressions for wcsrtombs optimizations"

Revert "Add valgrind suppressions for wcsrtombs optimizations"

This reverts commit 41344896364c4bf2229ec590c95cf23a6bec928e.

Per discussion, it's not desirable to add valgrind suppressions for
outside our own code base (e.g. glibc in this case), especially when
the suppressions may be platform-specific. There are better ways to
deal with that, e.g. by providing local suppressions.

Discussion: https://www.postgresql.org/message-id/flat/90ac0452-e907-e7a4-b3c8-15bd33780e62%402ndquadrant.com