CI: Run 128-bit SVE tests natively on dedicated ARM runner

128-bit SVE matches native ARMv9 hardware (Neoverse V2 / Google Axion)
and can execute directly in silicon on our dedicated ARM runner.

- In ci/build.linux.gitlab-ci.yml, remove CMAKE_CROSSCOMPILING_EMULATOR
  from build:linux:cross:sve:gcc-13:vl128 so CTest does not prefix test
  targets with qemu-aarch64.
- In ci/test.linux.gitlab-ci.yml, update .test:linux:sve:vl128 to extend
  .test:linux directly (dropping QEMU TCG timeout overrides and test
  exclusions), install native g++-13, and target tags [eigen-runner,
  linux, aarch64, sve].
- Retain synthetic 256-bit and 512-bit vector length tests under QEMU
  on SaaS runners.

ci/build.linux.gitlab-ci.yml

diff --git a/ci/build.linux.gitlab-ci.yml b/ci/build.linux.gitlab-ci.yml
index cb88827..6949462 100644
--- a/ci/build.linux.gitlab-ci.yml
+++ b/ci/build.linux.gitlab-ci.yml
@@ -667,6 +667,8 @@
 # architecturally legal but unimplemented, and compile-only coverage of them
 # bought two latent compile fixes at the cost of running nothing -- if a wider
 # part ships, add it here with a test job rather than as a build on its own.
+# 128-bit SVE matches native ARMv9 hardware (Neoverse V2 / Axion) and runs natively
+# on our ARM runner without QEMU emulation.
 build:linux:cross:sve:gcc-13:vl128:
   extends: .build:linux:cross:sve:gcc-13
   variables:
@@ -674,7 +676,6 @@
       -DEIGEN_TEST_SVE=ON
       -DEIGEN_TEST_SVE_VL=128
       -DEIGEN_TEST_CUSTOM_CXX_FLAGS=-march=armv8.2-a+sve
-      -DCMAKE_CROSSCOMPILING_EMULATOR=qemu-aarch64;-L;/usr/aarch64-linux-gnu
 
 build:linux:cross:sve:gcc-13:vl512:
   extends: .build:linux:cross:sve:gcc-13

ci/test.linux.gitlab-ci.yml

diff --git a/ci/test.linux.gitlab-ci.yml b/ci/test.linux.gitlab-ci.yml
index 1ed3530..fe6c6e2 100644
--- a/ci/test.linux.gitlab-ci.yml
+++ b/ci/test.linux.gitlab-ci.yml
@@ -603,11 +603,20 @@
 # job would silently run at the wrong width and pass against packet types built
 # for another. The sve_vector_length test compares RDVL against
 # EIGEN_ARM64_SVE_VL and fails if this is ever wrong.
+# 128-bit SVE matches native ARMv9 hardware (Neoverse V2 / Axion) and runs natively
+# on our dedicated ARM runner with zero QEMU emulation.
 .test:linux:sve:vl128:
-  extends: .test:linux:sve
+  extends: .test:linux
   needs: [ build:linux:cross:sve:gcc-13:vl128 ]
   variables:
-    QEMU_CPU: max,sve128=on,sve-default-vector-length=16
+    EIGEN_CI_TARGET_ARCH: aarch64
+    EIGEN_CI_CROSS_TARGET_TRIPLE: aarch64-linux-gnu
+    EIGEN_CI_INSTALL: g++-13
+  tags:
+    - eigen-runner
+    - linux
+    - aarch64
+    - sve
 
 .test:linux:sve:vl256:
   extends: .test:linux:sve