Disable automated inter-branch merges (dotnet#58061)

Author: wtgodbe

github-merge-flow.jsonc

@@ -1,20 +1,5 @@
 // IMPORTANT: This file is read by the merge flow from main branch only. 
 {
     "merge-flow-configurations": {
-        // Automate opening PRs to merge release/9.0 to main
-        "release/9.0":{
-            "MergeToBranch": "main",
-            "ExtraSwitches": "-QuietComments"
-        },
-        // Automate opening PRs to merge release/9.0-rc1 to release/9.0
-        "release/9.0-rc1":{
-            "MergeToBranch": "release/9.0",
-            "ExtraSwitches": "-QuietComments"
-        },
-        // Automate opening PRs to merge release/9.0-rc2 to release/9.0
-        "release/9.0-rc2":{
-            "MergeToBranch": "release/9.0",
-            "ExtraSwitches": "-QuietComments"
-        }
     }
-}
+}