ci(jest): remove detectOpenHandles flag
ci(jest): remove detectOpenHandles flag

The detectOpenHandles flag was added to help pin down an issue that we
were facing with some of our tests a while back. This flag comes with a
very high performance penalty and is no longer needed in our setup.

LN-Zap/zap-desktop,LN-Zap/zap-desktop,LN-Zap/zap-desktop