tests: regression: fix bogus error due to bash

tests: regression: fix bogus error due to bash

This suppresses several superfluous errors:

 any/meta.t: ERROR: line 168: nft add rule ip test-ip4 input meta iifgroup {11,33}: This rule should not have failed.
 any/meta.t: ERROR: line 178: nft add rule ip test-ip4 input meta oifgroup {11,33}: This rule should not have failed.
 ip/masquerade.t: ERROR: line 23: nft add rule ip4 test-ip4 output tcp dport {1,2,3,4,5,6,7,8,101,202,303,1001,2002,3003} masquerade: This rule should not have failed.
 ip6/masquerade.t: ERROR: line 23: nft add rule ip6 test-ip6 output tcp dport {1,2,3,4,5,6,7,8,101,202,303,1001,2002,3003} masquerade: This rule should not have failed.

This needs a space before the list of elements in the set, otherwise
bash here misinterprets the set.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>