fix(workflows): fix reminder email localization and location rendering

[abdulbaqui17]

Summary

Closes #28685.

This fixes workflow reminder email localization/rendering issues by:

1. Preventing undefined from appearing in the location line when meetingUrl is missing.
2. Omitting the location block when both location and meeting URL are empty.
3. Using locale-aware date formatting for runtime reminder emails.
4. Localizing "Scheduling by" in custom workflow email branding (instead of hardcoded English).
5. Updating German reminder copy:
   • hi -> Hallo
   • email_reminder_upcoming_event_notice -> Dies ist eine Erinnerung an Ihren bevorstehenden Termin.

Changes

• packages/features/ee/workflows/lib/reminders/templates/emailReminderTemplate.ts
  • safer location string construction
  • conditional location section rendering
  • locale-aware date rendering for non-edit mode
• packages/features/ee/workflows/lib/reminders/templates/customTemplate.ts
  • added optional schedulingByLabel parameter for localized branding
• packages/features/ee/workflows/lib/service/EmailWorkflowService.ts
• packages/features/ee/workflows/api/scheduleEmailReminders.ts
• packages/features/ee/workflows/lib/reminders/emailReminderManager.ts
  • pass translated scheduling_by into customTemplate for email HTML
• packages/i18n/locales/de/common.json
  • updated German reminder strings

Tests

Added:

• packages/features/ee/workflows/lib/reminders/templates/emailReminderTemplate.test.ts
  • ensures no undefined in reminder location output
  • ensures empty location section is omitted
• packages/features/ee/workflows/lib/reminders/templates/customTemplate.test.ts
  • ensures localized branding label is used

Ran:

• TZ=UTC yarn test packages/features/ee/workflows/lib/reminders/templates/emailReminderTemplate.test.ts packages/features/ee/workflows/lib/reminders/templates/customTemplate.test.ts
• NODE_OPTIONS='--max-old-space-size=8192' yarn type-check:ci --force

[cubic-dev-ai]

No issues found across 8 files

[abdulbaqui17]

@calcom/reviewers could a maintainer please add the run-ci label? The required check is currently failing on trust-gate for external contributors, so full CI has not run yet.