Prefix InterruptedCode's UNSPECIFIED with the enum name

It's a best practice because in C++ all protobuf enum values under a
message share one namespace.

RELNOTES: None.
PiperOrigin-RevId: 294742246

src/main/java/com/google/devtools/build/lib/server/GrpcServerImpl.java

@@ -615,7 +615,7 @@ private void executeCommand(RunRequest request, BlockingStreamObserver<RunRespon
     } catch (InterruptedException e) {
       result =
           BlazeCommandResult.failureDetail(
-              FailureDetailUtil.interrupted(InterruptedCode.UNSPECIFIED));
+              FailureDetailUtil.interrupted(InterruptedCode.INTERRUPTED_UNSPECIFIED));
       commandId = ""; // The default value, the client will ignore it
     }
 

src/main/protobuf/failure_details.proto

@@ -94,7 +94,7 @@ message FailureDetail {
 message Interrupted {
   enum InterruptedCode {
     // Interrupted at an unspecified time.
-    UNSPECIFIED = 0 [(metadata) = { exit_code: 8 }];
+    INTERRUPTED_UNSPECIFIED = 0 [(metadata) = { exit_code: 8 }];
     // TODO(mschaller): Add subcategories that specify what was happening at the
     //  time of interruption.
   }

src/test/java/com/google/devtools/build/lib/server/GrpcServerTest.java

@@ -400,7 +400,7 @@ public void onCompleted() {
     assertThat(secondResponse.get().hasFailureDetail()).isTrue();
     assertThat(secondResponse.get().getFailureDetail().hasInterrupted()).isTrue();
     assertThat(secondResponse.get().getFailureDetail().getInterrupted().getCode())
-        .isEqualTo(InterruptedCode.UNSPECIFIED);
+        .isEqualTo(InterruptedCode.INTERRUPTED_UNSPECIFIED);
   }
 
   @Test