before this change, we increment the refcount when constructing
`cct` instrusive_ptr, but nobody owns this smart pointer. also,
`CephContext` 's constructor set its refcount to 1. so, when the
test finishes, the refcount is 1, and this leads to a leakage of
the `CephContext` instance. and LeakSanitizer points this out:
```
Indirect leak of
10880000 byte(s) in 1 object(s) allocated from:
#0 0xaaaac359c7c8 in operator new(unsigned long) (/home/jenkins-build/build/workspace/ceph-pull-requests-arm64/build/bin/unittest_rgw_iam_policy+0x211c7c8) (BuildId:
060fadb10da261b52fd5757c7b1e9812d34542f1)
#1 0xffff96f764e4 in __gnu_cxx::new_allocator<ceph::logging::ConcreteEntry>::allocate(unsigned long, void const*) /usr/bin/../lib/gcc/aarch64-linux-gnu/11/../../../../include/c++/11/ext/new_allocator.h:127:27
#2 0xffff96f757cc in std::allocator<ceph::logging::ConcreteEntry>::allocate(unsigned long) /usr/bin/../lib/gcc/aarch64-linux-gnu/11/../../../../include/c++/11/bits/allocator.h:185:32
#3 0xffff96f757cc in boost::circular_buffer<ceph::logging::ConcreteEntry, std::allocator<ceph::logging::ConcreteEntry> >::allocate(unsigned long) /home/jenkins-build/build/workspace/ceph-pull-requests-arm64/build/boost/include/boost/circular_buffer/base.hpp:2396:39
#4 0xffff96f75500 in boost::circular_buffer<ceph::logging::ConcreteEntry, std::allocator<ceph::logging::ConcreteEntry> >::initialize_buffer(unsigned long) /home/jenkins-build/build/workspace/ceph-pull-requests-arm64/build/boost/include/boost/circular_buffer/base.hpp:2494:18
#5 0xffff96f6ec4c in boost::circular_buffer<ceph::logging::ConcreteEntry, std::allocator<ceph::logging::ConcreteEntry> >::circular_buffer(unsigned long, std::allocator<ceph::logging::ConcreteEntry> const&) /home/jenkins-build/build/workspace/ceph-pull-requests-arm64/build/boost/include/boost/circular_buffer/base.hpp:1039:9
#6 0xffff96f63528 in ceph::logging::Log::Log(ceph::logging::SubsystemMap const*) /home/jenkins-build/build/workspace/ceph-pull-requests-arm64/src/log/Log.cc:53:5
#7 0xffff96045300 in ceph::common::CephContext::CephContext(unsigned int, ceph::common::CephContext::create_options const&) /home/jenkins-build/build/workspace/ceph-pull-requests-arm64/src/common/ceph_context.cc:729:16
#8 0xffff960446ec in ceph::common::CephContext::CephContext(unsigned int, code_environment_t, int) /home/jenkins-build/build/workspace/ceph-pull-requests-arm64/src/common/ceph_context.cc:697:5
#9 0xaaaac3629238 in IPPolicyTest::IPPolicyTest() /home/jenkins-build/build/workspace/ceph-pull-requests-arm64/src/test/rgw/test_rgw_iam_policy.cc:864:15
#10 0xaaaac3628da0 in IPPolicyTest_MaskedIPOperations_Test::IPPolicyTest_MaskedIPOperations_Test() /home/jenkins-build/build/workspace/ceph-pull-requests-arm64/src/test/rgw/test_rgw_iam_policy.cc:869:1
#11 0xaaaac3628d3c in testing::internal::TestFactoryImpl<IPPolicyTest_MaskedIPOperations_Test>::CreateTest() /home/jenkins-build/build/workspace/ceph-pull-requests-arm64/src/googletest/googletest/include/gtest/internal/gtest-internal.h:472:44
```
so, in this change, we do not increase the refcount when creating cct.
Signed-off-by: Kefu Chai <tchaikov@gmail.com>