maintainers.inc: drop lsb4 perl modules no longer in core

maintainers.inc: drop lsb4 perl modules no longer in core

The following perl module packages were removed from oe-core
with commit: 30fb4c8f329fe3aa3c528ffeba60ee7d702e873e
  - libclass-isa-perl
  - libenv-perl
  - libdumpvalue-perl
  - libfile-checktree-perl
  - libi18n-collate-perl
  - libpod-plainer-perl

Remove these from the maintainers list

Fixes: [Yocto #12582]
(From OE-Core rev: 9eafd2d8bff2cb4949ee83bf7c5505bfcbad93d4)

Signed-off-by: Tim Orling <timothy.t.orling@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>