`test_spdm_responder` fails when run multiple times

[steven-bellock]

To reproduce run

./test_spdm_responder > /dev/null
./test_spdm_responder > /dev/null

The second time it is run will produce

[  ERROR   ] --- 0x7d != 0x7f
[   LINE   ] --- libspdm/unit_test/test_spdm_responder/set_key_pair_info_ack.c:191: error: Failure!
[  ERROR   ] --- 0x7d != 0x7f
[   LINE   ] --- libspdm/unit_test/test_spdm_responder/set_key_pair_info_ack.c:347: error: Failure!

Tests will pass again if the file libspdm/build/bin/cached_last_set_key_pair_info_request is deleted.

[steven-bellock]

@Xiaohanjlll as well.

[Xiaohanjlll]

I'll check it.

[Xiaohanjlll]

When the unit test is executed for the second time, the file "cached_last_set_key_pair_info_request" exists. Enter other branches.

https://github.com/DMTF/libspdm/blob/803849f3ab69c0fbc16dad31aa53696c4c9d5f06/os_stub/spdm_device_secret_lib_sample/lib.c#L2591-L2601 https://github.com/DMTF/libspdm/blob/803849f3ab69c0fbc16dad31aa53696c4c9d5f06/os_stub/spdm_device_secret_lib_sample/lib.c#L2632-L2689