Tests: workaround for QUIC routing while reloading nginx. Datagrams can be routed to a new worker process that lacks the connection state resulting in a stateless reset. Previously, the QUIC connection was closed in tests on decryption failure including receiving a stateless reset, which is not yet detected in HTTP3.pm. The workaround is to ignore packets that could not be decrypted including a stateless reset. This is enough to continue receiving packets from the old worker process, such as with GOAWAY.