Fixes multiple issues with CRON schedule input validation and execution
time display.
### Issues Fixed
1. **UTC label placement** - Added "UTC" suffix to specific times (e.g.,
"at 09:30 UTC") but not to interval descriptions (e.g., "every hour")
2. **Upcoming execution time calculation** - Fixed incorrect execution
times for malformed CRON expressions by implementing auto-correction
### Changes
- Created `normalizeCronExpression` utility to standardize cron
expressions before parsing
- Updated `formatTime` to support optional UTC suffix
- Enhanced `getHoursDescription` to append UTC to specific times
- Added comprehensive test coverage (102 tests passing)
### Before
- `"1 /3 * * *"` showed daily executions at same time (incorrect)
- `"9 * * *"` showed same time repeated 3 times (incorrect)
- No UTC labels on schedule descriptions (confusing)
### After
- All malformed expressions auto-corrected and show correct execution
times
- UTC labels clearly indicate timezone for specific times
- User-friendly error messages for truly invalid patterns
Closes#15870
