add g6.12xlarge for multi gpu tests (#7124)

# Overview
add g6.12xlarge instance as ephmeral

# purpose
as we want to enable more vllm tests in ci, replace h100 4 gpu instance
with g6.12xlarge for vllm tests. bc currently we have limited h100
https://instances.vantage.sh/aws/ec2/g6.12xlarge?currency=USD

Author: yangw-dev

.github/canary-scale-config.yml

@@ -147,6 +147,11 @@ runner_types:
     instance_type: g6.4xlarge
     is_ephemeral: true
     os: linux
+  c.linux.g6.12xlarge.nvidia.gpu:
+    disk_size: 150
+    instance_type: g6.12xlarge
+    is_ephemeral: true
+    os: linux
   c.linux.large:
     disk_size: 15
     instance_type: c5.large

.github/lf-canary-scale-config.yml

@@ -147,6 +147,11 @@ runner_types:
     instance_type: g6.4xlarge
     is_ephemeral: true
     os: linux
+  lf.c.linux.g6.12xlarge.nvidia.gpu:
+    disk_size: 150
+    instance_type: g6.12xlarge
+    is_ephemeral: true
+    os: linux
   lf.c.linux.large:
     disk_size: 15
     instance_type: c5.large

.github/lf-scale-config.yml

@@ -147,6 +147,11 @@ runner_types:
     instance_type: g6.4xlarge
     is_ephemeral: true
     os: linux
+  lf.linux.g6.12xlarge.nvidia.gpu:
+    disk_size: 150
+    instance_type: g6.12xlarge
+    is_ephemeral: true
+    os: linux
   lf.linux.large:
     disk_size: 15
     instance_type: c5.large

.github/scale-config.yml

@@ -143,6 +143,11 @@ runner_types:
     instance_type: g6.4xlarge
     is_ephemeral: true
     os: linux
+  linux.g6.12xlarge.nvidia.gpu:
+    disk_size: 150
+    instance_type: g6.12xlarge
+    is_ephemeral: true
+    os: linux
   linux.large:
     disk_size: 15
     instance_type: c5.large