Make test_interest_suppression more robust.  refs #100165
Make test_interest_suppression more robust.  refs #100165

Use env for setting CCND_DEBUG (more portable across versions of sh).
Sync startup of ccnd4 for this test.
Bail if prefix reg fails (probably won't now, with startup sync).
Use trap for tearing down test-specific ccnd.

cawka/ndnx,svartika/ccnx,svartika/ccnx,svartika/ccnx,ebollens/ccnmp,cawka/ndnx,ebollens/ccnmp,svartika/ccnx,cawka/ndnx,cawka/ndnx,svartika/ccnx,ebollens/ccnmp,ebollens/ccnmp,svartika/ccnx,svartika/ccnx,cawka/ndnx