Fix mt_update and mt_upsert WHERE clauses for partitioned tables

[jeremydmiller]

Summary

• Fix mt_update_* function to include partition columns in WHERE clause alongside id = docId
• Fix SELECT mt_version statements in both mt_update_* and mt_upsert_* to include partition columns
• Previously, updating a document with the same ID but different partition key would target all rows matching the ID, causing duplicate key violations

Closes #4223

What Changed

• UpsertFunction.cs — build _andPartitionWhereClause from partition columns, append to all WHERE/SELECT clauses
• UpdateFunction.cs — append _andPartitionWhereClause to UPDATE WHERE and SELECT WHERE clauses

Example

For a table with PK (id, date):

-- Before (broken):
UPDATE mt_doc_snapshot SET ... WHERE id = docId;

-- After (fixed):
UPDATE mt_doc_snapshot SET ... WHERE id = docId AND date = arg_date;

Test plan

• 2 tests: update and upsert with same id + different partition key both correctly target single rows

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