Cleanup the DUNECI_CMAKE_FLAGS for a failing job

.gitlab-ci.yml

@@ -27,7 +27,8 @@ debian-11-gcc-9-17-with-checking:
   script: duneci-standard-test
   variables:
     DUNECI_TOOLCHAIN:   gcc-9-17
-    DUNECI_CMAKE_FLAGS:   "CC=gcc-9 CXX=g++-9 -DCMAKE_CXX_FLAGS='-std=c++17 -O2 -g -Wall -fdiagnostics-color=always -DDUNE_ISTL_WITH_CHECKING' -DDUNE_MAX_TEST_CORES=4 -DCMAKE_DISABLE_FIND_PACKAGE_LATEX=TRUE -DCMAKE_DISABLE_FIND_PACKAGE_Alberta=TRUE -DCMAKE_DISABLE_DOCUMENTATION=TRUE"
+    DUNECI_CXXFLAGS: "-DDUNE_ISTL_WITH_CHECKING"
+    DUNECI_CMAKE_FLAGS: "-DDUNE_MAX_TEST_CORES=4 -DCMAKE_DISABLE_FIND_PACKAGE_LATEX=TRUE -DCMAKE_DISABLE_FIND_PACKAGE_Alberta=TRUE -DCMAKE_DISABLE_DOCUMENTATION=TRUE"
   tags: [duneci]
 
 # no numpy version available for this image on the gitlab registry