[test suite] Fix GPG SPA cycles that do not require 'no pw' key pairs

Add gpg.conf and gpg-agent.conf to set 'pinentry-mode loopback' to
restore GPG full cycle tests. This works with GPG 2.2.27 on Ubuntu. The
specific error that is fixed is shown at the end of the output below:

[.] client_send_spa_packet() executing client and looking for fwknopd
receiving packet, try: 1
Sat Feb  3 11:55:56 2024 CMD: LD_LIBRARY_PATH=../lib/.libs
../client/.libs/fwknop -A tcp/22 -a 127.0.0.2 -D 127.0.0.1 --get-key
local_spa.key --no-save-args --verbose --verbose --gpg-recipient-key
361BBAD4 --gpg-signer-key 6A3FAD56 --gpg-home-dir
/home/mbr/git/fwknop.git/test/conf/client-gpg --rc-file
/home/mbr/git/fwknop.git/test/conf/fwknoprc_gpg_hmac_sha512_key
fwknop: fko_spa_data_final: Error 122 - Error during the encrypt and
sign operation
GPG ERR: Inappropriate ioctl for device