fix crash in CtfSpecialSeedGenerator occuring at run boundaries (73X version of #6418 )



move theRegionProducer delete to the destructor
fixes problems online
discussed in
https://hypernews.cern.ch/HyperNews/CMS/get/edmFramework/3395/2/1/1/2/1.html

tested in CMSSW_7_2_1_patch1 using the online DQM setup (crash is gone) and then with short matrix to see no differences in output as expected.

same code diff as in #6418