Almost-adjacent committee memberships should keep 'member since' date
On a committee page, the 'member since' date should ignore small gaps of 1 day in membership history, since these are typically administration errors.
See e.g. @lscholten's Technicie membership.
When a member has a 1-day gap (member from t to t+x, chair from t+x+1 to now), the join date is reset to the new membership's starting date (i.e. t+x+1).
When a member has a 1-day gap (member from t to t+x, chair from t+x+1 to now), the join date should be the original join date (i.e. t).
Steps to reproduce
- Create a membership from t to t+2years
- Create a membership from t+2years+1day to now
- Observe that 'committee member since' says 't+2years', not 't'