FINERACT-2721: Fix loan collateral quantity adjustment and modify-loan change detection

[Samer-Melhem-FOO]

Description

Two related defects in loan collateral handling (LoanCollateralAssembler / LoanAssemblerImpl):

1. Repeated quantity deduction. LoanCollateralAssembler.fromParsedJson(...) deducted client collateral quantity on every call, including from read-only paths (loan application validation, schedule preview), not just actual loan submission/update. Since the same parsing method is reused across both, a client's available collateral quantity could be decremented more than once for the same loan, and submitting a loan with linked collateral could fail with an "invalid amount of collateral quantity" error even with sufficient collateral available.

2. Inverted change detection on loan modification. In LoanAssemblerImpl, the check that decides whether collateral changed on a Modify Loan Application request was inverted:

   possiblyModifedLoanCollateralItems.equals(loan.getLoanCollateralManagements())

   This recorded a "collateral changed" entry (and triggered loan.updateLoanCollateral(...)) only when the new and existing collateral sets were equal — i.e. when nothing changed — and skipped it when they genuinely differed. Real collateral changes on loan modification were silently dropped.

Fix: LoanCollateralAssembler.fromParsedJson now takes an explicit adjustClientCollateralQuantity flag, defaulting to false for read-only/validation callers (existing single-arg overload preserved) and true only for actual loan submission/update. The modify-loan condition is flipped to !equals(...) so genuine changes are detected and persisted.

JIRA: https://issues.apache.org/jira/browse/FINERACT-2721

Checklist

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Note: no existing unit/integration test covers LoanCollateralAssembler/LoanAssemblerImpl's collateral-handling logic, so none were added — happy to add coverage if a reviewer points to the right harness (loan submission with collateral is normally exercised via integration tests).

[Samer-Melhem-FOO]

The only failing check here (MariaDB Tests (Shard 14 of 15)) is CobPartitioningTest.testLoanCOBPartitioningQuery() failing with Expected status code <200> but was <403> — a permission/auth assertion in the Close-of-Business job partitioning test suite. This PR only touches LoanCollateralAssembler and LoanAssemblerImpl (collateral quantity handling), and doesn't touch permissions, job scheduling, or COB logic at all, so this looks like pre-existing test flakiness rather than something introduced here.

Would appreciate a re-run of that job when convenient — happy to investigate further if it fails again on a fresh run.