Makefile: set PRIVILEGED_TESTS env in tests-privileged target
Makefile: set PRIVILEGED_TESTS env in tests-privileged target

Instead of specifying build tags, privileged tests are now run by setting the
PRIVILEGED_TESTS environment variable added in a prior commit.

Since packages can now no longer be filtered by 'privileged_tests' build
tags, remove PRIV_TEST_PKGS.

Signed-off-by: Timo Beckers <98c2d5a1e48c998bd9ba9dbc53d6857beae1c9bd@isovalent.com>

cilium/cilium,cilium/cilium,cilium/cilium,cilium/cilium,cilium/cilium