various valgrind leak on connection lost, config cache connection with wrong pwd and operations while changing password

As part of libcouchbase migration 3.0.6 in the Amadeus Couchbase client, we encountered some leak running valgrind memcheck tools.

Reproducer to implement in Lcb:

1/ Connection lost with mock

After connection and traffic, stop the mock then run an operation (ie. set).

2/ Bootstrap with config cache file with wrong pwd

using bootstrap_on=file_only & config_cache_ro=topo.conf

3/ Operations while changing password 

After connection and traffic, we change password on server side then run an operation (ie. set).