ci: remove unused tag DEBIAN_X86_64_TEST_IMAGE_PATH
DEBIAN_X86_64_TEST_IMAGE_PATH is unused and DEBIAN_X86_TEST_IMAGE_GL_PATH doesn't even exist, so remove it to avoid confusion.
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DEBIAN_X86_64_TEST_IMAGE_PATH is unused and DEBIAN_X86_TEST_IMAGE_GL_PATH doesn't even exist, so remove it to avoid confusion.