osmo-auc-gen: umts: use default of ind_bitlen = 5 instead of 0

Most USIM out there seem to use IND-length = 5 bits, so do sysmousim-sjs1.
Currently from initialization we are using an IND length of zero in
osmo-auc-gen, which produces confusing SQN results after AUTS:

Where want SQN to be incremented to the next IND array, usually +32, an IND-len
of 0 makes for only +1.

As result, the osmo-auc-gen_test.sh produces SQN 32 instead of 24 after
receiving SQN.MS = 23 from AUTS: adjust test expectations.

Related: OS#2465
Change-Id: I9fcc11fa2b5816302dcc6b72249b1ee40d5a61f5
diff --git a/utils/osmo-auc-gen.c b/utils/osmo-auc-gen.c
index 87960ae..4e07fa7 100644
--- a/utils/osmo-auc-gen.c
+++ b/utils/osmo-auc-gen.c
@@ -138,6 +138,7 @@
 			break;
 		case '3':
 			test_aud.type = OSMO_AUTH_TYPE_UMTS;
+			test_aud.u.umts.ind_bitlen = 5;
 			break;
 		case 'a':
 			rc = osmo_auth_alg_parse(optarg);