[Fix-18286] Use real existing workerGroups more accurately instead of defaulting to 'default'

[KaiSong-UK]

close #18286

Purpose

When user configures custom workerGroup (e.g. g_suyc) and there is no default group in workerGroup management list, the system still defaults to default as workerGroup in the API layer, causing ambiguity and potential errors when:

• Creating/updating schedules (project preferences)
• Executing workflows
• Starting workflow/task checks

This is a server-side fix that removes the hardcoded defaultValue = " default\ in the API controllers, allowing the upstream logic to handle the default based on actual available workerGroups.

Changes

• SchedulerController.java: Removed defaultValue = \default\ from createSchedule, updateSchedule, updateScheduleByWorkflowDefinitionCode methods
• ExecutorController.java: Removed defaultValue = \default\ from startCheckResult, execTaskInstance, execute methods

Verify

• Verify this PR is a improvement for the issue [Improvement][ApiServer] Use real existing workerGroups more accurately instead of defaulting to 'default', to avoid ambiguity. #18286.

[SbloodyS]

This issue has been claimed by the author, and only the issue labeled good first issue is the first contributor-friendly issue.