TSAN: LogUtil::GetLogPrefix data race

[mapleFU]

The code in [1] calls std::localtime, which might not thread safe [2]. Sample as

WARNING: ThreadSanitizer: data race (pid=119895)
  Write of size 8 at 0x7b04000007d0 by thread T50:
    #0 free /home/admin/llvm/llvm-project-17.0.3.src/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp:722:3 (cz_fs_unittest+0x28fba05)
    #1 tzset_internal /home/lyukefan/deps/glibc-2.18/time/tzset.c:440:3 (libc.so.6+0xab3da)
    #2 qcloud_cos::LogUtil::GetLogPrefix(int) <null> (cz_fs_unittest+0x3526295)

  Previous write of size 8 at 0x7b04000007d0 by thread T65:
    #0 malloc /home/admin/llvm/llvm-project-17.0.3.src/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp:663:5 (cz_fs_unittest+0x28fb2ac)
    #1 __strdup /home/lyukefan/deps/glibc-2.18/string/strdup.c:42:15 (libc.so.6+0x84a7a)
    #2 qcloud_cos::LogUtil::GetLogPrefix(int)

[1] https://github.com/tencentyun/cos-cpp-sdk-v5/blob/549a3affecc0d851a8947b9684c2a09e458aadf8/src/util/log_util.cpp#L20C47-L20C62
[2] https://github.com/tencentyun/cos-cpp-sdk-v5/blob/549a3affecc0d851a8947b9684c2a09e458aadf8/src/util/log_util.cpp#L20C47-L20C62

[mapleFU]

@Huberyxiao would you mind take a look?