chore: format schedule commands

• Please check this box if this contribution uses AI-generated content (including content generated by GitLab Duo features) as outlined in the GitLab DCO & CLA. As a benefit of being a GitLab Community Contributor, you receive complimentary access to GitLab Duo.

What does this MR do?

This MR standardizes the CLI help display formatting for schedule commands by updating the Example sections in the schedule command files to follow the style guide outlined in issue #7841 (closed):

• Commands start with $
• Results start with >
• Comments start with #

Updated files:

• commands/schedule/create/create.go
• commands/schedule/delete/delete.go
• commands/schedule/list/list.go
• commands/schedule/run/run.go
• commands/schedule/update/update.go

Example of changes:

Before:

Example: heredoc.Doc(`
    glab schedule create --cron "0 * * * *" --cmd "echo 'hello world'"
    
    # creates a pipeline schedule that runs every hour
`),

After:

Example: heredoc.Doc(`
    # Create a pipeline schedule that runs every hour
    $ glab schedule create --cron "0 * * * *" --cmd "echo 'hello world'"
    > Pipeline schedule created successfully
`),

Related issues

Closes #7841 (closed)

MR acceptance checklist

• All files have been updated according to the style guide

• Documentation has been updated if necessary