Revert "testing/tests/download: test git special ref"

This reverts commit 81771cfcdc40e5909a4ec663e7c88b3a32068c05.

The download of sha1 of a special ref currently works or not depending
on the git client version in use.
With git version 2.11.0 (present in the docker image) it does not work.
With git version 2.17.1 it works.

For the sake of reproducibility, remove this part of the TestGitRefs
test case until some code gets added to the download infra to handle
sha1 of a special ref for any git client version.

Fixes:
https://gitlab.com/buildroot.org/buildroot/-/jobs/158295269

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

support/testing/tests/download/br2-external/git-refs/package/git-special-ref/git-special-ref.hash

@@ -1,2 +0,0 @@
-sha256  e78abd24049c6acac81a02fb8fa6dfa60db74a19772d41e28ad9d6b9b77c8054  git-special-ref-b72ff6078f62522a87f5cae5e9f34dedf5ec3885.tar.gz
-sha256  b252b594be4679764e2e06cfea77a3e50638dd445af9b472b0f298c43b134518  file

support/testing/tests/download/br2-external/git-refs/package/git-special-ref/git-special-ref.mk

@@ -1,11 +0,0 @@
-################################################################################
-#
-# git-special-ref
-#
-################################################################################
-
-GIT_SPECIAL_REF_VERSION = b72ff6078f62522a87f5cae5e9f34dedf5ec3885
-GIT_SPECIAL_REF_SITE = git://localhost:$(GITREMOTE_PORT_NUMBER)/repo.git
-GIT_SPECIAL_REF_LICENSE_FILES = file
-
-$(eval $(generic-package))

support/testing/tests/download/git-remote/repo.git/refs/changes/01/1/2

@@ -1 +0,0 @@
-b72ff6078f62522a87f5cae5e9f34dedf5ec3885

support/testing/tests/download/test_git.py

@@ -76,7 +76,6 @@ class TestGitRefs(GitTestBase):
         self.check_download("git-sha1-reachable-by-tag")
         self.check_download("git-sha1-tag-itself")
         self.check_download("git-sha1-tag-points-to")
-        self.check_download("git-special-ref")
         self.check_download("git-submodule-disabled")
         self.check_download("git-submodule-enabled")
         self.check_download("git-tag")