fix: #3605768 Convert SchemaFactory static caches to instance properties

TokenValidationDataPreProcessor::process() calls setFormat(NULL) on the cached Swaggest Schema object. Because SchemaFactory stored compiled schemas in static class properties, the mutation persisted across PHP-FPM requests, permanently removing format constraints for all subsequent requests on the same worker.

Convert $schemasCache and $decodedSchemaCache to instance properties. Each DI-managed SchemaFactory instance (one per HTTP request) gets its own cache. clearCache() changes from static to instance method.

Closes #3605768