FINERACT-2844: Fix PostgreSQL standing instruction loan-dues query

[rhopman]

Description

Updates the Execute Standing Instruction job to use a database-compatible boolean predicate when retrieving incomplete loan repayment schedules. This prevents PostgreSQL’s boolean <> integer error while preserving MySQL and MariaDB compatibility.

Adds PostgreSQL coverage verifying that outstanding loan dues are calculated from due, incomplete installments while completed and future installments are excluded.

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