LU-5079 tests: fix service_time in max_recovery_time()

This patch fixes the calculation of service_time in
max_recovery_time() to use the new method in
check_and_start_recovery_timer() and new values of
CONNECTION_SWITCH_MAX and CONNECTION_SWITCH_INC.

The patch also fixes replay-dual sub-tests:
- to call wait_clients_import_state() instead of sleeping
  uncertain time in test_11()
- to add some margin into the recovery time comparison
  in test_20()

Test-Parameters: alwaysuploadlogs \
envdefinitions=SLOW=yes,ENABLE_QUOTA=yes,REPLAY_DUAL_EXCEPT=21 \
mdtfilesystemtype=ldiskfs mdsfilesystemtype=ldiskfs \
ostfilesystemtype=ldiskfs mdtcount=1 \
testlist=replay-dual,replay-dual

Signed-off-by: Jian Yu <jian.yu@intel.com>
Change-Id: Ife0fab28ed7b67ac61022f7e8a38957e3995b167
Reviewed-on: http://review.whamcloud.com/12724
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>