monitor/linaro.json: Remove libcxx buildbots

These are all buildkite bots now. Status for those
coming once I get hold of an API key for buildkite.

Change-Id: I6aae10e62bbed43d799c6b233f0106395d02e4cf
diff --git a/monitor/linaro.json b/monitor/linaro.json
index 6f0403f..4ef51be 100644
--- a/monitor/linaro.json
+++ b/monitor/linaro.json
@@ -54,17 +54,6 @@
         ]
       },
       {
-        "name": "Library Bots",
-        "bots": [
-          { "name": "libcxx-libcxxabi-libunwind-armv7-linux" },
-          { "name": "libcxx-libcxxabi-libunwind-armv7-linux-noexceptions" },
-          { "name": "libcxx-libcxxabi-libunwind-armv8-linux" },
-          { "name": "libcxx-libcxxabi-libunwind-armv8-linux-noexceptions" },
-          { "name": "libcxx-libcxxabi-libunwind-aarch64-linux" },
-          { "name": "libcxx-libcxxabi-libunwind-aarch64-linux-noexceptions" }
-        ]
-      },
-      {
         "name": "LLD Bots",
         "bots": [
           { "name": "clang-cmake-armv8-lld" },