ASan: heap-use-after-free on `Configuration` during bucket destroy

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==25686==ERROR: AddressSanitizer: heap-use-after-free on address 0x6070004182f8 at pc 0x7fc48fe80bfe bp 0x7fc4865d3050 sp 0x7fc4865d3048

READ of size 8 at 0x6070004182f8 thread T34 (mc:bucket_del)

    #0 0x7fc48fe80bfd in std::_Rb_tree<...>::find() const /usr/local/include/c++/7.3.0/bits/stl_tree.h:2533

    #1 0x7fc48fe81ce6 in std::map<...>::find() const /usr/local/include/c++/7.3.0/bits/stl_map.h:1189

    #2 0x7fc48fe81ce6 in unsigned long Configuration::getParameter<unsigned long>(...) const kv_engine/engines/ep/src/configuration.cc:171

    #3 0x7fc48fead5f9 in Configuration::getDcpConnBufferSize() const build/kv_engine/engines/ep/src/generated_configuration.cc:591

    #4 0x7fc48fa9d249 in DcpFlowControlManager::setBufSizeWithinBounds(DcpConsumer*, unsigned long&) kv_engine/engines/ep/src/dcp/flow-control-manager.cc:49

    #5 0x7fc48fa9ef2d in DcpFlowControlManagerAggressive::handleDisconnect(DcpConsumer*) kv_engine/engines/ep/src/dcp/flow-control-manager.cc:202

    #6 0x7fc48fa59cf2 in DcpConsumer::~DcpConsumer() kv_engine/engines/ep/src/dcp/consumer.cc:187

<cut shared_ptr details...>

    #19 0x7fc48f9c1cb7 in AtomicQueue<std::shared_ptr<ConnHandler> >::~AtomicQueue() kv_engine/engines/ep/src/atomicqueue.h:39

    #20 0x7fc48f9c1cb7 in ConnMap::~ConnMap() kv_engine/engines/ep/src/connmap.cc:106

    #21 0x7fc48fa8c4b7 in DcpConnMap::~DcpConnMap() kv_engine/engines/ep/src/dcp/dcpconnmap.cc:63

    #22 0x7fc48fa8c4b7 in DcpConnMap::~DcpConnMap() kv_engine/engines/ep/src/dcp/dcpconnmap.cc:65

    #23 0x7fc48fb9d41c in std::default_delete<DcpConnMap>::operator()(DcpConnMap*) const /usr/local/include/c++/7.3.0/bits/unique_ptr.h:78

    #24 0x7fc48fb9d41c in std::unique_ptr<DcpConnMap, std::default_delete<DcpConnMap> >::~unique_ptr() /usr/local/include/c++/7.3.0/bits/unique_ptr.h:268

    #25 0x7fc48fb9d41c in EventuallyPersistentEngine::~EventuallyPersistentEngine() kv_engine/engines/ep/src/ep_engine.cc:5772

    #26 0x7fc48fb9da8e in EventuallyPersistentEngine::~EventuallyPersistentEngine() kv_engine/engines/ep/src/ep_engine.cc:5780

    #27 0x7fc48fb9da8e in EventuallyPersistentEngine::destroy(bool) kv_engine/engines/ep/src/ep_engine.cc:154

    #28 0x44299e in DestroyBucketThread::destroy() kv_engine/daemon/memcached.cc:1980

0x6070004182f8 is located 40 bytes inside of 80-byte region [0x6070004182d0,0x607000418320)

freed by thread T34 (mc:bucket_del) here:

    #0 0x7fc49a5c16b0 in operator delete(void*) (install/bin/../lib/libasan.so.4+0xdb6b0)

<cut shared_ptr details...>

    #8 0x7fc48fe77232 in Configuration::~Configuration() kv_engine/engines/ep/src/configuration.h:178

    #9 0x7fc48fb9d38b in EventuallyPersistentEngine::~EventuallyPersistentEngine() kv_engine/engines/ep/src/ep_engine.cc:5772

    #10 0x7fc48fb9da8e in EventuallyPersistentEngine::~EventuallyPersistentEngine() kv_engine/engines/ep/src/ep_engine.cc:5780

    #11 0x7fc48fb9da8e in EventuallyPersistentEngine::destroy(bool) kv_engine/engines/ep/src/ep_engine.cc:154

    #12 0x44299e in DestroyBucketThread::destroy() kv_engine/daemon/memcached.cc:1980

    #13 0x4439ee in DestroyBucketThread::run() kv_engine/daemon/memcached.cc:2012

    #14 0x7fc498801ff0 in Couchbase::Thread::thread_entry() platform/src/thread.cc:45

    #15 0x7fc4987d57d8 in CouchbaseThread::run() platform/src/cb_pthreads.cc:59

    #16 0x7fc4987d57d8 in platform_thread_wrap platform/src/cb_pthreads.cc:72

    #17 0x7fc496bd06b9 in start_thread (/lib/x86_64-linux-gnu/libpthread.so.0+0x76b9)