test uses +d,getnameinfo_fake_long_host to return a fake long
hostname in ip_to_hostname(). But this dbug keyword is only checked
after the lookup in the hostname cache.
the test has to flush the hostname cache in case previous tests
had it populated with fake ip addresses (perfschema tests do that)
also, remove redundant `connection` directives
Also increase user name up to 128.
The work was started by Rucha Deodhar <rucha.deodhar@mariadb.com>,
contains audit plugin fixes by Alexey Botchkov <holyfoot@askmonty.org>.
