Update named configurations on builders, turn off checking temporarily.

The named configurations aren't used yet, and checking that they agree
with the existing flags will now just print error messages, not make
the builder fail.

Change-Id: Ia0778855d3c45da8e3314f9cff0967ec1fc7893b
Reviewed-on: https://dart-review.googlesource.com/67807
Reviewed-by: William Hesse <whesse@google.com>

tools/bots/test_matrix.json

@@ -149,6 +149,7 @@
         "runtime": "vm",
         "mode": "release",
         "preview-dart-2": false,
+        "use-sdk": true,
         "checked": true,
         "timeout": 240
       }},
@@ -157,6 +158,7 @@
         "compiler": "none",
         "runtime": "vm",
         "mode": "release",
+        "use-sdk": true,
         "enable-asserts": true
       }},
     "unittest-analyzer_use_fasta-linux": {

tools/testing/dart/configuration.dart

@@ -422,7 +422,6 @@ class TestConfiguration {
             "Configuration and namedConfiguration differ: ${toSummaryMap()} $namedConfiguration"
             "$builderTag ${namedConfiguration.builderTag}");
         isValid = false;
-        exit(1);
       }
     }