Remove dump-macro flag in test

Author: natecook1000

test/stdlib/Observation/Observable.swift

@@ -1,6 +1,6 @@
 // REQUIRES: swift_swift_parser, executable_test
 
-// RUN: %target-run-simple-swift( -Xfrontend -dump-macro-expansions -Xfrontend -disable-availability-checking -parse-as-library -enable-experimental-feature InitAccessors -enable-experimental-feature Macros -enable-experimental-feature ExtensionMacros -Xfrontend -plugin-path -Xfrontend %swift-host-lib-dir/plugins)
+// RUN: %target-run-simple-swift( -Xfrontend -disable-availability-checking -parse-as-library -enable-experimental-feature InitAccessors -enable-experimental-feature Macros -enable-experimental-feature ExtensionMacros -Xfrontend -plugin-path -Xfrontend %swift-host-lib-dir/plugins)
 
 // Run this test via the swift-plugin-server
 // RUN: %target-run-simple-swift( -Xfrontend -disable-availability-checking -parse-as-library -enable-experimental-feature InitAccessors -enable-experimental-feature Macros -enable-experimental-feature ExtensionMacros -Xfrontend -external-plugin-path -Xfrontend %swift-host-lib-dir/plugins#%swift-plugin-server)