On Ubuntu Bionic (where CURL library depends on RTMP library) keyring_vault unit tests can be build and run without any issues (all clean including ASan and Valgrind). However, by default they are disabled by CHECK_IF_CURL_DEPENDS_ON_RTMP CMake macro.
To test, just disable CHECK_IF_CURL_DEPENDS_ON_RTMP() calls in
build and run
./mysql-test/mtr --debug-server main.1st --unit-tests
Consider eliminating this macro and build keyring_vault unit tests unconditionally.