unittests: fix leaks reported by ASan

[PragmaTwice]

use std::unique_ptr to avoid missing delete and dtor call

this fix can remove a large amount of leak reports from ASan (~10000+ lines in stderr), so we can check easier when other important leaks is reported.

[tisonkun]

@PragmaTwice could you share the ASan report before and after this change?

[PragmaTwice]

@PragmaTwice could you share the ASan report before and after this change?

The ASan report before this is about 6MiB, I will soon find a way to upload. Seems reach the size limit in GitHub?

[PragmaTwice]

kvrocks-unittest-asan.log
kvrocks-unittest-asan-after.log

Seems just some error due to my poor network, not limit exceeding. Done @tisonkun.

[tisonkun]

@PragmaTwice looks great! It seems that this PR fixes all leaks currently reported. We should fail if there are new leaks in #599.

[git-hulk]

LGTM, cool!

[PragmaTwice]

@PragmaTwice looks great! It seems that this PR fixes all leaks currently reported. We should fail if there are new leaks in #599.

Seems there are also some leaks in TCL tests, I do not know the current status, maybe @git-hulk know that.
In #599, ASan is enabled in daily-ci.yaml, dont know whether it should be added to kvrocks.yaml.

ASan will slow down the program execution about x2 times, and TSan about x10 times.
Refer to https://clang.llvm.org/docs/AddressSanitizer.html and https://clang.llvm.org/docs/ThreadSanitizer.html.

[git-hulk]

Yes, I can reproduce the memory leak on my side, but didn't investigate root causes now.

[tisonkun]

I'm going to merge this PR.

Further discussion about #599 can go to that thread. If you'd like to investigate leak issues, it'd be better to create another issue.