Allow non-composable raw SQL queries for TPH non-root types

[roji]

In #18232, we allowed non-composable raw SQL queries for TPH root types, by eliminating the discriminator predicate when it is configured as complete. However, it is still impossible to use non-compsable raw SQL for querying non-root types.

I'm guessing that was discussed before, but... we could say that with raw SQL queries, it's the user's responsibility to write the SQL such that only the correct entity type comes back, and therefore not add the discriminator predicate in EF. If the user's SQL is wrong, unexpected entity types will come back and materialization would fail.

Originally requested by @kobruleht in npgsql/efcore.pg#1700

[ajcvickers]

@smitpatel to find general issue.

[kobruleht]

Maybe FromSqlRaw queries should not modified by EF Core.

This would allow to use multiple Sql commands ending with semicolon in query.

Posted also in https://www.postgresql.org/message-id/c18b027c-4629-58a5-a499-64dc8a233e8f%40hot.ee

[smitpatel]

Related #21888