In LDAP test, restart after pg_hba.conf changes

In LDAP test, restart after pg_hba.conf changes

Instead of issuing a reload after pg_hba.conf changes between test
cases, run a full restart.  With a reload, an error in the new
pg_hba.conf is ignored and the tests will continue to run with the old
settings, invalidating the subsequent test cases.  With a restart, a
faulty pg_hba.conf will lead to the test being aborted, which is what
we'd rather want.