send unrequested ack when we haven't acked more than 100 stanza. Fixes

gajim/gajim#8758
2 jobs for asterix/master in 9 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #1711
run-test

00:00:05

 
  Build
passed #1712
run-build

00:00:04