Server should start new elections if it was voter in previous configuration

[freeekanayaka]

During a membership change, a leader being removed should still start elections, see section 4.2.2:

Second, a server that is not part of its own latest configuration should still start
new elections, as it might still be needed until the Cnew entry is committed (as in Figure 4.6). It does
not count its own vote in elections unless it is part of its latest configuration