Add HOME env var to ipa-server-configure.service

[stlaz]

OpenSSL requires at least one of HOME or RANDFILE environment
variables to be set for it to work.

Without this fix, the external CA setup crashes because OpenSSL
is unable to write its random state anywhere when it tries to
generate a CSR for the external CA to sign.

[adelton]

Reading man systemd.exec(5) I don't see expansion of tilda documented.

[adelton]

OTOH, there is

       $USER, $LOGNAME, $HOME, $SHELL
           User name (twice), home directory, and the login shell. The
           variables are set for the units that have User= set, which
           includes user systemd instances. See passwd(5).

so maybe User=root would do the trick?

[stlaz]

That also works and is probably cleaner. Rebased and updated the commit message.

[adelton]

Based on https://bugzilla.redhat.com/show_bug.cgi?id=1524833#c28, maybe RANDFILE=/dev/null would actually be the best approach. Data that we don't store cannot cause problems during upgrades, for example. ;-)

[stlaz]

Updated and deployed testing.

[stlaz]

Tests passed, merging.