fix build: change zstd and yaml-cpp in Find*.cmake to be compatible …

[botanegg]

…with upstream names

required to fix errors and warnings when -DCMAKE_FIND_PACKAGE_PREFER_CONFIG=ON

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[apolukhin]

Error on Debian:

The link interface of target "RocksDB::rocksdb" contains:

    zstd::zstd

  but the target was not found.  Possible reasons include:

    * There is a typo in the target name.
    * A find_package call is missing for an IMPORTED target.
    * An ALIAS target is missing.

Call Stack (most recent call first):
  /usr/lib/x86_64-linux-gnu/cmake/rocksdb/RocksDBConfig.cmake:87 (include)
  cmake/SetupRocksDB.cmake:10 (find_package)
  rocks/CMakeLists.txt:3 (include)