[vm] DBC is obsolete. Remove dead code.

Change-Id: Ica33af158cca53c8e951e4b2582de83660e8a60d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/121851
Commit-Queue: Samir Jindel <sjindel@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>

tools/test.dart

@@ -99,13 +99,9 @@ String archOfBuilder(String builder) {
       (component) => [
             "arm",
             "arm64",
-            "armsimdbc",
-            "armsimdbc64",
             "ia32",
             "simarm",
             "simarm64",
-            "simdbc",
-            "simdbc64",
             "x64",
           ].contains(component),
       orElse: () => null);