fix(turboquant): drop ignore-eos patch, bump fork to b8967-627ebbc (#9423)

* fix(turboquant): drop ignore-eos patch, bump fork to b8967-627ebbc

The upstream PR #21203 (server: respect the ignore_eos flag) has been
merged into the TheTom/llama-cpp-turboquant feature/turboquant-kv-cache
branch. With the fix now in-tree, 0001-server-respect-the-ignore-eos-flag.patch
no longer applies (git apply sees its additions already present) and the
nightly turboquant bump fails.

Retire the patch and bump the pin to the first fork revision that carries
the merged fix (tag feature-turboquant-kv-cache-b8967-627ebbc). This matches
the contract in apply-patches.sh: drop patches once the fork catches up.

* fix(turboquant): patch out get_media_marker() call in grpc-server copy

CI turboquant docker build was failing with:

  grpc-server.cpp:2825:40: error: use of undeclared identifier
  'get_media_marker'

The call was added by 7809c5f5 (PR #9412) to propagate the mtmd random
per-server media marker upstream landed in ggml-org/llama.cpp#21962. The
TheTom/llama-cpp-turboquant fork branched before that PR, so its
server-common.cpp has no such symbol.

Extend patch-grpc-server.sh to substitute get_media_marker() with the
legacy "<__media__>" literal in the build-time grpc-server.cpp copy
under turboquant-<flavor>-build/. The fork's mtmd_default_marker()
returns exactly that string, and the Go layer falls back to the same
sentinel when media_marker is empty, so behavior on the turboquant path
is unchanged. Patched copy only — the shared source under
backend/cpp/llama-cpp/ keeps compiling against vanilla upstream.

Verified by running `make docker-build-turboquant` locally end-to-end:
all five flavors (avx, avx2, avx512, fallback, grpc+rpc-server) now
compile past the previous failure and the image tags successfully.