At most 2 GPUs for CI (#27435)

At most 2 GPUs
Co-authored-by: ydshieh <ydshieh@users.noreply.github.com>

.github/workflows/self-nightly-scheduled.yml

@@ -19,6 +19,7 @@ env:
   SIGOPT_API_TOKEN: ${{ secrets.SIGOPT_API_TOKEN }}
   TF_FORCE_GPU_ALLOW_GROWTH: true
   RUN_PT_TF_CROSS_TESTS: 1
+  CUDA_VISIBLE_DEVICES: 0,1
 
 jobs:
   setup:

.github/workflows/self-past.yml

@@ -30,6 +30,7 @@ env:
   SIGOPT_API_TOKEN: ${{ secrets.SIGOPT_API_TOKEN }}
   TF_FORCE_GPU_ALLOW_GROWTH: true
   RUN_PT_TF_CROSS_TESTS: 1
+  CUDA_VISIBLE_DEVICES: 0,1
 
 jobs:
   setup:

.github/workflows/self-push.yml

@@ -25,6 +25,7 @@ env:
   PYTEST_TIMEOUT: 60
   TF_FORCE_GPU_ALLOW_GROWTH: true
   RUN_PT_TF_CROSS_TESTS: 1
+  CUDA_VISIBLE_DEVICES: 0,1
 
 jobs:
   setup:

.github/workflows/self-scheduled.yml

@@ -23,6 +23,7 @@ env:
   SIGOPT_API_TOKEN: ${{ secrets.SIGOPT_API_TOKEN }}
   TF_FORCE_GPU_ALLOW_GROWTH: true
   RUN_PT_TF_CROSS_TESTS: 1
+  CUDA_VISIBLE_DEVICES: 0,1
 
 jobs:
   setup: