ggsn: Delete previously activated pdp ctx in *_interact()

This change fixes some GGSN_Tests failing lately since osmo-ggsn
correctly sends DeleteCtxReq for dangling pdp ctx upon increased
Recovery counter received, and tests are not expecting that (because
they don't expectect dangling pdp ctx from previous tests).

Change-Id: I232298e2bfd8bfc99d82cbf5803d11db7eb1786a
diff --git a/ggsn_tests/GGSN_Tests.ttcn b/ggsn_tests/GGSN_Tests.ttcn
index 4a53fa1..44dba4a 100644
--- a/ggsn_tests/GGSN_Tests.ttcn
+++ b/ggsn_tests/GGSN_Tests.ttcn
@@ -958,6 +958,7 @@
 		f_wait_gtpu_fail(ctxB);
 
 		f_pdp_ctx_del(ctxA, '1'B);
+		f_pdp_ctx_del(ctxB, '1'B);
 	}
 
 	/* Test PDP context activation for dynamic IPv4 EUA without DNS request */
@@ -1089,6 +1090,7 @@
 		f_wait_icmp4_echo_request(ctxB);
 
 		f_pdp_ctx_del(ctxA, '1'B);
+		f_pdp_ctx_del(ctxB, '1'B);
 	}
 
 	/* Validate if different clients (pdp ctx) can reach one another through GGSN. */
@@ -1345,6 +1347,7 @@
 		f_wait_gtpu_fail(ctxB);
 
 		f_pdp_ctx_del(ctxA, '1'B);
+		f_pdp_ctx_del(ctxB, '1'B);
 	}
 
 	/* Test IPv4v6 context activation for dynamic IPv4v6 EUA on a v4-only APN */