Modifying Supercronic Related Code in start.sh

[kimzuni]

Context

1. Before registering Supercronic, check the size of the crontab file, not variables value.
2. If you perform the task registered in Supercronic, the log as like:
   

Choices

1. If you modify it this way, you don't need to modify it even if related functions are added.
2. Add the -passthrough-logs option to Supercronic so that the standard output of the file is displayed normally.
   

Test instructions

1. Set the BACKUP_ENABLED variable to false so that nothing is stored in the crontab file, and check whether the else part is executed.
2. Set the BACKUP_ENABLED or AUTO_UPDATE_ENABLED variable to true to see if it goes to the if part, and check the log on which update was executed.

Checklist before requesting a review

• I have performed a self-review/test of my code
• I've not introduced breaking changes.
• My changes do not violate linting rules.

[thijsvanloef]

Love this change!