Fix form page freezing

[gaspergrom]

Changes proposed ✍️

What

🤖 Generated by Copilot at 6cde9a8

Refactored onMounted hook and getMemberCustomAttributes function in member-form-page.vue to use promises instead of async/await. This improves the page performance and UI responsiveness.
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🤖 Generated by Copilot at 6cde9a8

onMounted hook
uses promise, not await
faster UI now

Why

How

🤖 Generated by Copilot at 6cde9a8

• Refactor onMounted hook to use promise-based approach instead of async/await (link)
• Remove unnecessary async modifier from getMemberCustomAttributes function (link)

Checklist ✅

• Label appropriately with Feature, Improvement, or Bug.
• Add screehshots to the PR description for relevant FE changes
• New backend functionality has been unit-tested.
• API documentation has been updated (if necessary) (see docs on API documentation).
• Quality standards are met.