[Housekeeping] Deleted CRON schedule shorthands

[SmritiSatyanV]

Describe the issue

Keep tabs on flytekit to support CRON schedule shorthand.

Currently, flytekit doesn’t support this format but the scheduler does.Use the regular 5 field standard cron for now. Ensure that shorthands work with the upcoming flytekit versions

What if we do not do this?

Users won't be able to use CRON shorthands.

Related component(s)

No response

Are you sure this issue hasn't been raised already?

• [X] Yes

Have you read the Code of Conduct?

• [X] Yes