Use 128 bit AES for key control block

Merge from Widevine repo of http://go/wvgerrit/49805

This aligns the oemcrypto reference code and unit tests to match the
API design doc: http://go/oemcrypto

bug: 79375509
test: unit tests pass
Change-Id: I13761a7384a17e99d88e61aaf80b4a22941fd172

libwvdrmengine/oemcrypto/test/oec_session_util.h

@@ -378,9 +378,6 @@ class Session {
   // The size of the encrypted message.
   size_t message_size() { return message_size_; }
 
-  // If this session has an entitlement license.
-  bool has_entitlement_license() const { return has_entitlement_license_; }
-
  private:
   // Generate mac and enc keys give the master key.
   void DeriveKeys(const uint8_t* master_key,
@@ -410,7 +407,6 @@ class Session {
   vector<uint8_t> encrypted_usage_entry_;
   uint32_t usage_entry_number_;
   string pst_;
-  bool has_entitlement_license_;
 
   // Clear Entitlement key data. This is the backing data for
   // |entitled_key_array_|.