Adapt src/test/ldap/t/001_auth.pl to work with openldap 2.5.

ldapsearch's deprecated -h/-p arguments were removed, need to use -H now -
which has been around for over 20 years.

As perltidy insists on reflowing the parameters anyway, change order and
"phrasing" to yield a less confusing layout (per suggestion from Tom Lane).

Discussion: https://postgr.es/m/20211009233850.wvr6apcrw2ai6cnj@alap3.anarazel.de
Backpatch: 11-, where the tests were added.
