ci: test CDash submission tests on some nightly dashboards

One from each platform, and a mix of architectures and generators.

.gitlab/ci/configure_debian10_ninja.cmake

@@ -107,4 +107,8 @@ if (NOT "$ENV{SWIFTC}" STREQUAL "")
   set(CMAKE_Swift_COMPILER "$ENV{SWIFTC}" CACHE FILEPATH "")
 endif()
 
+if (NOT "$ENV{CMAKE_CI_NIGHTLY}" STREQUAL "")
+  set(CMAKE_TESTS_CDASH_SERVER "https://open.cdash.org" CACHE STRING "")
+endif()
+
 include("${CMAKE_CURRENT_LIST_DIR}/configure_external_test.cmake")

.gitlab/ci/configure_fedora38_makefiles_clang.cmake

@@ -1 +1,5 @@
+if (NOT "$ENV{CMAKE_CI_NIGHTLY}" STREQUAL "")
+  set(CMAKE_TESTS_CDASH_SERVER "https://open.cdash.org" CACHE STRING "")
+endif()
+
 include("${CMAKE_CURRENT_LIST_DIR}/configure_fedora38_common_clang.cmake")

.gitlab/ci/configure_macos_arm64_ninja_multi.cmake

@@ -1,5 +1,6 @@
 if (NOT "$ENV{CMAKE_CI_NIGHTLY}" STREQUAL "")
   set(CMake_TEST_ISPC "ON" CACHE STRING "")
+  set(CMAKE_TESTS_CDASH_SERVER "https://open.cdash.org" CACHE STRING "")
 endif()
 
 # FIXME: sccache sometimes fails with "Compiler killed by signal 9".

.gitlab/ci/configure_windows_vs2019_x64.cmake

@@ -1 +1,5 @@
+if (NOT "$ENV{CMAKE_CI_NIGHTLY}" STREQUAL "")
+  set(CMAKE_TESTS_CDASH_SERVER "https://open.cdash.org" CACHE STRING "")
+endif()
+
 include("${CMAKE_CURRENT_LIST_DIR}/configure_windows_vs_common.cmake")