Do not include HDK artifacts in Conda Env Cache

[alexbaden]

HDK artifacts from previous versions can interfere with the build step. We could modify the build step to preference locally built libraries, but it would be difficult to ensure we are using the built libraries instead of libraries from cache, and could introduce subtle bugs.

[alexbaden]

I switched to manually restoring/saving the cache instead of letting the action handle it. So far it seems to be working. I did notice the save cache prints this warning when the cache already exists:

Failed to save: Unable to reserve cache with key Linux-cuda-conda-pytest-bb2dc8e90e4ae27591e01a61d207f6aed1b987d349ed2832be6a4ba924ad5324-, another job may be creating this cache. More details: Cache already exists. Scope: refs/pull/416/merge, Key: Linux-cuda-conda-pytest-bb2dc8e90e4ae27591e01a61d207f6aed1b987d349ed2832be6a4ba924ad5324-, Version: 26f8beb5992dd4ad4275b1d61bdc64e789f4a3fedface27da0514df34062e47d
Warning: Cache save failed.

I don't think that is a problem.

[alexbaden]

With https://github.com/intel-ai/hdk/pull/416 I have included a change to manually restore and save the cache prior to installing pyhdk libraries, only for the PyHDK pytest job. I have run several times w/ and w/out debug and it appears to be working, but we will let it sit in main for a bit then apply the same change to all other jobs using conda env cache.