Updating 4xH100 to only run with tags or workflow dispatch (#2715)

Summary:
Currently we have a long queue, so would like to reduce it

Test Plan:

Reviewers:

Subscribers:

Tasks:

Tags:

Author: jerryzh168

.github/pytorch-probot.yml

@@ -3,3 +3,4 @@ ciflow_push_tags:
 - ciflow/benchmark
 - ciflow/tutorials
 - ciflow/rocm
+- ciflow/4xh100

.github/workflows/4xH100_tests.yml

@@ -4,11 +4,9 @@ on:
   push:
     branches:
       - main
-      - 'gh/**'
-  pull_request:
-    branches:
-      - main
-      - 'gh/**'
+    tags:
+      - ciflow/4xh100/*
+  workflow_dispatch:
 
 concurrency:
   group: 4xH100_tests-${{ github.workflow }}-${{ github.ref == 'refs/heads/main' && github.run_number || github.ref }}