Remove renewal related expectations from WvCdmStreamingPstTest.
Also clean up the code in cdm_extended_duration_test.cpp.
Bug: 19534907
Merged from Widevine CDM repo:
https://widevine-internal-review.googlesource.com/#/c/13842/
Change-Id: I89f9aafd80c8867af541b29bc8a6778f53a8b7e6