[Google Blockly] Modal Function Editor UI Fixes

[molly-moen]

2 small fixes to the modal function editor:

• remove width: 100% on the toolbar (delete/close buttons) as this was preventing click on part of the definition block.
• Change the delete button to be purple rather than white. We are adding a modal soon to confirm delete, and these colors are in line with the existing CDO Blockly colors

New Button Color

Links

• jira ticket: CT-141

Testing story

Tested locally

PR Checklist:

• Tests provide adequate coverage
• Privacy and Security impacts have been assessed
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked