refact: remove linux headless (#15866)

* refact: remove linux headless

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(linux): probe DRM availability asynchronously on login

Signed-off-by: fufesou <linlong1266@gmail.com>

* revert changes in drm_capturer.rs

Signed-off-by: fufesou <linlong1266@gmail.com>

* Update submodule hbb_common

Signed-off-by: fufesou <linlong1266@gmail.com>

* docs(linux): clarify DRM availability comments

Remove stale headless and unauthenticated-request
wording, and document the Available-only login-screen gate.

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(linux): remove unreachable session cleanup branch

Remove the obsolete empty-session path and
clarify the intended use of cached DRM availability.

Signed-off-by: fufesou <linlong1266@gmail.com>

---------

Signed-off-by: fufesou <linlong1266@gmail.com>

.github/workflows/ci.yml

@@ -124,7 +124,6 @@ jobs:
                gcc \
                git \
                g++ \
-               libpam0g-dev \
                libasound2-dev \
                libunwind-dev \
                libgstreamer1.0-dev \