Fix expand/collapse icon on saved schedules

[HeidiTao]

Description

Changed the hide button on the saved schedules page to "Show" when the schedule is collapsed; reversed the arrow directions to display the direction of the upcoming action (show-downwards, hide-upwards).
Examples:

Type of change

• UI fix (non-breaking change which improves UI)

How Has This Been Tested?

By adding test courses to saved schedules and clicking on the show/hide button.

Test Configuration:

Node.js version: v20.16.0
Desktop/Mobile: Desktop
OS: Windows
Browser: Chrome

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[railway-app]

This PR was not deployed automatically as @HeidiTao does not have access to the Railway project.

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[Xavilien]

LGTM