RFR: 8314730: GHA: Drop libfreetype6-dev transitional package in favor of libfreetype-dev

[Aleksey Shipilev]

Current GHA bootstraps fail for some arches with the incompatibility between libfreetype-dev and libfreetype6-dev. libfreetype6-dev. Current RISC-V GHA bootstrap fails due to this conflict.

In both sid and bullseye and sid, libfreetype6-dev is a transitional package:
  https://packages.debian.org/bullseye/libfreetype6-dev
  https://packages.debian.org/sid/libfreetype6-dev

There is therefore no reason to ask for libfreetype6-dev instead of libfreetype-dev. 

Additional testing:
 - [ ] GHA

-------------

Commit messages:
 - Actually, cannot build without freetype: cross-compiled builds look into sysroots for it
 - Drop freetype completely, as we ship one in JDK
 - Fix

Changes: https://git.openjdk.org/jdk/pull/15378/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15378&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8314730
  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/15378.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15378/head:pull/15378

PR: https://git.openjdk.org/jdk/pull/15378