Tests: Fix RunCMake.CMP0040 custom command syntax

Tests/RunCMake/CMP0040/CMP0040-NEW-existing-target.cmake

@@ -3,5 +3,5 @@ cmake_policy(SET CMP0040 NEW)
 add_library(foobar empty.cpp)
 
 add_custom_command(TARGET foobar PRE_BUILD
-  COMMAND "${CMAKE_COMMAND} -E echo hello world"
+  COMMAND ${CMAKE_COMMAND} -E echo hello world
 )

Tests/RunCMake/CMP0040/CMP0040-NEW-missing-target.cmake

@@ -1,5 +1,5 @@
 cmake_policy(SET CMP0040 NEW)
 
 add_custom_command(TARGET foobar PRE_BUILD
-  COMMAND "${CMAKE_COMMAND} -E hello world"
+  COMMAND ${CMAKE_COMMAND} -E hello world
 )

Tests/RunCMake/CMP0040/CMP0040-OLD-existing-target.cmake

@@ -3,5 +3,5 @@ cmake_policy(SET CMP0040 OLD)
 add_library(foobar empty.cpp)
 
 add_custom_command(TARGET foobar PRE_BUILD
-  COMMAND "${CMAKE_COMMAND} -E echo hello world"
+  COMMAND ${CMAKE_COMMAND} -E echo hello world
 )

Tests/RunCMake/CMP0040/CMP0040-OLD-missing-target.cmake

@@ -1,5 +1,5 @@
 cmake_policy(SET CMP0040 OLD)
 
 add_custom_command(TARGET foobar PRE_BUILD
-  COMMAND "${CMAKE_COMMAND} -E echo hello world"
+  COMMAND ${CMAKE_COMMAND} -E echo hello world
 )

Tests/RunCMake/CMP0040/CMP0040-WARN-missing-target.cmake

@@ -1,4 +1,4 @@
 
 add_custom_command(TARGET foobar PRE_BUILD
-  COMMAND "${CMAKE_COMMAND} -E hello world"
+  COMMAND ${CMAKE_COMMAND} -E hello world
 )