[docs] update build instruction for RHEL9 and newer

Starting with RHEL9, many core Perl modules were decoupled from the main
interpreter package, and perl-FindBin was one of them.  The module is
necessary to build PostgreSQL in 3rd-party from source.

This changelist introduces corresponding updates into the instructions
for building/installing Kudu on RHEL9 and newer.

Change-Id: I98bb4372c09424f35e7c4821a2be5b4fd0010848
Reviewed-on: http://gerrit.cloudera.org:8080/24843
Tested-by: Kudu Jenkins
Reviewed-by: Zoltan Martonka <zmartonka@cloudera.com>
Reviewed-by: Marton Greber <greber.mx@gmail.com>