Use rpmkeys --list in test cases

This indeed does work with the fs backend nowadays.
Since 42985d5 actually.

Keep the find in the first case to make sure the key is in the right
place. For the second test case the file is gone anyway.

tests/rpmsigdig.at

@@ -203,14 +203,15 @@ runroot rpmkeys -Kv /data/RPMS/hello-2.0-1.x86_64-signed-with-new-subkey.rpm
 [])
 
 RPMTEST_CHECK([
-# XXX rpmkeys --list doesn't yet work with fs keystore
-runroot_other find /usr/lib/sysimage/rpm/pubkeys -name "*.key" | wc -l
+runroot rpmkeys --list | wc -l
 runroot rpmkeys --import /data/keys/rpm.org-rsa-2048-add-subkey.asc
+runroot rpmkeys --list | wc -l
 runroot_other find /usr/lib/sysimage/rpm/pubkeys -name "*.key" | wc -l
 ],
 [0],
 [1
 1
+1
 ],
 [])
 
@@ -243,8 +244,7 @@ runroot rpmkeys --delete 1964c5fc
 [])
 
 RPMTEST_CHECK([
-# XXX rpmkeys --list doesn't yet work with fs keystore
-runroot_other find /usr/lib/sysimage/rpm/pubkeys -name "*.key" | wc -l
+runroot rpmkeys --list | wc -l
 ],
 [0],
 [0