Use ParseFromTString/ParseFromArray for tstring.
Use ParseFromTString/ParseFromArray for tstring.

1) This change elides an implicit copy to std::string.
2) Implicit conversion from tstring to std::string was added temporarily in
order to ease migration to tstring; implicit
`tstring::operator std::string() const' is now being deprecated.
3) ParseFromStringPiece is not available in external proto compilers.

PiperOrigin-RevId: 293226987

tensorflow/lingvo,tensorflow/lingvo,tensorflow/lingvo,tensorflow/lingvo