Update train_type_t enum to support all combinations of flags
Update train_type_t enum to support all combinations of flags

Summary:
It looks like loading FAISS codecs which have the flag set fails in dev mode since it builds in ASAN and nothing in the code checks for that.
The error is not present in opt mode, however the sandcastle test fails
For best practice, this diff introduces combination of train_type_t flags as enums

Reviewed By: mdouze

Differential Revision: D32746904

fbshipit-source-id: f20820350e0b07b35e04c965dee01b790194e6f3

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