Remove Sub-Licenses and Sub-Sessions

(This is a merge of http://go/wvgerrit/66643)

The sub-license feature has been removed from the server and packager.
So that we do not have to continue maintaining the code that supports
this feature that never shipped, I am removing it from the CDM as well.

Bug: 113165466
Test: CE CDM Unit Tests
Test: Android Unit Tests
Change-Id: I5d25844b161e74aa19adf19a29c56e4881aa7304

libwvdrmengine/cdm/core/include/policy_engine.h

@@ -59,11 +59,6 @@ class PolicyEngine {
   // permits playback.
   virtual void SetLicense(const video_widevine::License& license);
 
-  // TODO(jfore): Sublicense uses this to update the keys when they are
-  // changed during key rotation. Drop this method and use SetLicenseKeys
-  // instead.
-  virtual void UpdateLicenseKeys(const video_widevine::License& license);
-
   // Used to update the currently loaded entitled content keys.
   virtual void SetEntitledLicenseKeys(
       const std::vector<WidevinePsshData_EntitledKey>& entitled_keys);