swarm: fix network/stream data races (#19051)

* swarm/network/stream: newStreamerTester cleanup only if err is nil

* swarm/network/stream: raise newStreamerTester waitForPeers timeout

* swarm/network/stream: fix data races in GetPeerSubscriptions

* swarm/storage: prevent data race on LDBStore.batchesC

https://github.com/ethersphere/go-ethereum/issues/1198#issuecomment-461775049

* swarm/network/stream: fix TestGetSubscriptionsRPC data race

https://github.com/ethersphere/go-ethereum/issues/1198#issuecomment-461768477

* swarm/network/stream: correctly use Simulation.Run callback

https://github.com/ethersphere/go-ethereum/issues/1198#issuecomment-461783804

* swarm/network: protect addrCountC in Kademlia.AddrCountC function

https://github.com/ethersphere/go-ethereum/issues/1198#issuecomment-462273444

* p2p/simulations: fix a deadlock calling getRandomNode with lock

https://github.com/ethersphere/go-ethereum/issues/1198#issuecomment-462317407

* swarm/network/stream: terminate disconnect goruotines in tests

* swarm/network/stream: reduce memory consumption when testing data races

* swarm/network/stream: add watchDisconnections helper function

* swarm/network/stream: add concurrent counter for tests

* swarm/network/stream: rename race/norace test files and use const

* swarm/network/stream: remove watchSim and its panic

* swarm/network/stream: pass context in watchDisconnections

* swarm/network/stream: add concurrent safe bool for watchDisconnections

* swarm/storage: fix LDBStore.batchesC data race by not closing it