tests: Capture player output via journal instead of client

Capturing the client's output tests both client and server, which is
nice.  However, player input isn't visible in the resulting file,
which makes it more difficult to understand.

Route player output to journal (econfig key "keep_journal 2"), and
ignore client output.

Separate tests for the client would be useful.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>

tests/test-common.sh

@@ -18,7 +18,7 @@ data "../../var/empire"
 info "../../../../info.nr"
 builtin "../../share/empire/builtin"
 listen_addr "$EMPIREHOST"
-keep_journal 1
+keep_journal 2
 EOF
     cp "$srcdir"/src/lib/global/*.config sandbox/share/empire/builtin
 }