Tested following the same curl and tshark commands as in commit
"vtls: Extract and simplify key log file handling from OpenSSL" using
WolfSSL v4.4.0-stable-128-g5179503e8 from git master built with
`./configure --enable-all --enable-debug CFLAGS=-DHAVE_SECRET_CALLBACK`.
Full support for this feature requires certain wolfSSL build options,
see "Availability note" in lib/vtls/wolfssl.c for details.
Closes#5327