Fix activity type filter display

[joanagmaia]

Changes proposed ✍️

Currently we are receiving custom activity types outside of "other" object in settings. This PR fixes the platform display that groups the activity types in the activity type filter:

• Show "Custom" if activity types are inside "other"
• Show default platform name if platform exists in our configuration (e.g. github)
• Show platform key coming from settings if platform doesn't exist in our settings and is not inside other

What

🤖 Generated by Copilot at f317c34

Improved activity type labels for undefined platforms. Modified getActivityTypes in activity-type-field.js to use the activity type key as the label, unless it is 'other'.
​

🤖 Generated by Copilot at f317c34

getActivityTypes
More precise labels now
Fall leaves no confusion

Why

How

🤖 Generated by Copilot at f317c34

• Handle undefined platform name in activity type labels (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.