Add unit tests for org.apache.texera.web.resource pure-logic helpers

[Yicong-Huang]

Task Summary

amber/src/main/scala/org/apache/texera/web/resource/ has ~30 files of which ~7 ship with tests. A self-contained cluster of pure-logic helpers — no DB, no servlet container, no auth — can be covered in one PR:

• EmailTemplate.scala — userRegistrationNotification admin / user branches, createRoleChangeTemplate; subject/content shape and the [deployment] suffix toggle off UserSystemConfig.appDomain.
• dashboard/FulltextSearchQueryUtils.scala — getFullTextSearchFilter pgroonga / fallback branches and empty-input guards, getContainsFilter set-based OR, getDateFilter open-ended ranges and ParseException, getOperatorsFilter LIKE construction.
• dashboard/hub/EntityTables.scala — BaseEntityTable / LikeTable / CloneTable / ViewCountTable dispatch maps for WORKFLOW and DATASET entity types.
• HealthCheckResource.scala — single-method status map.
• SuccessExecutionResult.scala — case-class defaults.

Out of scope (heavier mocking, follow-ups):

• SystemMetadataResource — needs OperatorMetadataGenerator bootstrap
• WorkflowWebsocketResource / CollaborationResource — need a javax.websocket.Session double
• UserConfigResource — DB-backed, follow-up like Add DB-backed unit tests for ExecutionsMetadataPersistService and ExecutionStateStore.updateWorkflowState #5210 / test(amber): DB-backed unit tests for ExecutionsMetadataPersistService and updateWorkflowState #5213
• SyncExecutionResource / GmailResource — large, already have partial coverage
• Dashboard-resource cluster (Workflow / Hub / Project / etc.) — DB-heavy, separate bundles

Task Type

• Testing / QA