chore(appeals): removing NET_RESIDENCE feature flag infra changes (A2-7240)

[julietteorpen]

Describe your changes

This PR follows on from the work done in this PR, removing redundant code.
It removes all infra relating to the NET_RESIDENCE feature flag

Tests:
When excluding NET_RESIDENCE_S20, all four grep commands return zero results:

 grep -r 'featureFlagNetResidence' . | grep -v 'featureFlagNetResidenceS20'
 grep -r 'FEATURE_FLAG_NET_RESIDENCE' . | grep -v 'FEATURE_FLAG_NET_RESIDENCE_S20'
 grep -r 'FEATURE_FLAG_NAMES.NET_RESIDENCE' . | grep -v 'NET_RESIDENCE_S20' 
 grep -r 'NET_RESIDENCE' . | grep -v 'NET_RESIDENCE_S20' 

Issue ticket number and link

Ticket