Revert "llvmbot monitor: Move Arm lldb to silent"

This reverts commit 5d4f334634b04ba47dde08e9f8c0ff869d02ad03.

We have not seen the failure since the fix was committed.
(https://github.com/llvm/llvm-project/issues/96750)

Change-Id: Ic539fd67fbb9632381c3f66829887c5906f0d669
diff --git a/monitor/linaro.json b/monitor/linaro.json
index 3cadbcc..637062c 100644
--- a/monitor/linaro.json
+++ b/monitor/linaro.json
@@ -52,6 +52,7 @@
         "name": "LLDB",
         "bots": [
           { "name": "lldb-aarch64-ubuntu" },
+          { "name": "lldb-arm-ubuntu" },
           { "name": "lldb-aarch64-windows" }
         ]
       },
@@ -76,19 +77,5 @@
         ]
       }
     ]
-  },
-  {
-    "name": "LLVM Silent Master",
-    "base_url": "https://lab.llvm.org/staging",
-    "builder_url": "builders",
-    "build_url": "builds",
-    "builders": [
-      {
-        "name": "LLDB",
-        "bots": [
-          { "name": "lldb-arm-ubuntu" }
-        ]
-      }
-    ]
   }
 ]