gitlab: add testing for flux-sched on system instance clusters

Problem: We need to be testing flux-sched's integration with the
rest of the framework, and we're not.

Do that on corona and tioga since they're the system-instance clusters.

Note that due to missing RPATH entries for certain libraries in Cray's
compilers, this currently needs to be compiled with GCC. Also, the
Valgrind test is temporarily exempted because it fails due to a memory
leak in hwloc.

.gitlab-ci.yml

@@ -78,6 +78,23 @@ default:
         - make -j $(nproc) check
         - make -j $(nproc) install
 
+.test-sched:
+    extends: .lc-variables
+    variables:
+        PYTHON: "/usr/bin/python3"
+        debug: t
+        FLUX_TESTS_LOGFILE: t
+    script:
+        - cd ${CI_DIRECTORY}
+        - export PKG_CONFIG_PATH=${CORE_INSTALL_PREFIX}/lib/pkgconfig:$(pkg-config --variable pc_path pkg-config)
+        - git clone https://github.com/flux-framework/flux-sched
+        - cd flux-sched
+        - module load gcc 
+        - ${CORE_INSTALL_PREFIX}/bin/flux ./configure
+        - make -j $(nproc)
+        - make -j $(nproc) install
+        - ctest -j 16 -E "t5000-valgrind.t"
+
 .test-core-mpi:
     extends: .lc-variables
     ## this will need coral2 XOR pmix depending on system (hopefully both eventually)
@@ -101,6 +118,13 @@ corona-core-test:
         - .corona
     stage: test
 
+corona-sched-test:
+    needs: ["corona-core-build"]
+    extends:
+        - .test-sched
+        - .corona
+    stage: test
+
 poodle-core-build:
     extends: 
         - .build-core
@@ -140,6 +164,13 @@ tioga-coral2-test:
         - .tioga
     stage: test
 
+tioga-sched-test:
+    needs: ["tioga-core-build"]
+    extends:
+        - .test-sched
+        - .tioga
+    stage: test
+
 tioga-mpi-test:
     needs: ["tioga-core-build", "tioga-coral2-test"]
     extends: