When trying to extract the key ID from a key file name, some test code
incorrectly attempts to strip all leading zeros. This breaks tests when
keys with ID 0 are generated. Add a new helper shell function,
keyfile_to_key_id(), which properly handles keys with ID 0 and use it in
test code whenever a key ID needs to be extracted from a key file name.
(cherry picked from commit 7d6eaad1bd)
6045adbd1a