Tests: Allow RunCMake.MaxRecursionDepth to test public-facing default limit

Previously we compiled in a smaller default limit during nightly testing
and CI builds, so we were not testing the same default limit that
end-users will see.  Instead, set the limit during testing using an
environment variable so that we can unset it when testing the default
limit in `RunCMake.MaxRecursionDepth`.

Source/CMakeLists.txt

@@ -12,9 +12,7 @@ endif()
 include(CheckIncludeFile)
 
 if(NOT CMake_DEFAULT_RECURSION_LIMIT)
-  if(DEFINED ENV{DASHBOARD_TEST_FROM_CTEST})
-    set(CMake_DEFAULT_RECURSION_LIMIT 100)
-  elseif(MINGW OR MSYS)
+  if(MINGW OR MSYS)
     set(CMake_DEFAULT_RECURSION_LIMIT 400)
   elseif(WIN32 AND CMAKE_C_COMPILER_ARCHITECTURE_ID STREQUAL "ARM64")
     set(CMake_DEFAULT_RECURSION_LIMIT 400)

Tests/EnforceConfig.cmake.in

@@ -35,5 +35,8 @@ unset(ENV{CMAKE_GENERATOR_PLATFORM})
 unset(ENV{CMAKE_GENERATOR_TOOLSET})
 unset(ENV{CMAKE_EXPORT_COMPILE_COMMANDS})
 
+# Verify that our module implementations do not recurse too much.
+set(ENV{CMAKE_MAXIMUM_RECURSION_DEPTH} 100)
+
 @TEST_HOME_ENV_CODE@
 @TEST_WARN_VS_CODE@