Disable Vivado nightlies

Vivado randomly fails with the following error message:

    FATAL_ERROR: Vivado Simulator kernel has discovered an exceptional
    condition from which it cannot recover. Process will terminate. For
    technical support on this issue, please open a WebCase with this
    project attached at http://www.xilinx.com/support.

Until we have a way of retrying these test cases or marking them as
skipped, these nightlies have been disabled to prevent a "boy who cried
wolf" situtation.

.ci/gitlab/test.yml

@@ -179,29 +179,40 @@ ffi:example:
   after_script:
     - tar -cf - /root/.cabal | zstd -T${THREADS} -3 > cache.tar.zst
 
+# XXX: Vivado randomly fails with the following error message:
+#
+#          FATAL_ERROR: Vivado Simulator kernel has discovered an exceptional
+#          condition from which it cannot recover. Process will terminate. For
+#          technical support on this issue, please open a WebCase with this
+#          project attached at http://www.xilinx.com/support.
+#
+#      Until we have a way of retrying these test cases or marking them as
+#      skipped, these nightlies have been disabled to prevent a "boy who cried
+#      wolf" situtation.
+#
 # Tests run on local fast machines with Vivado installed. We only run these at night
 # to save resources - as Vivado is quite slow to execute.
-.test-cache-local-nightly:
-  extends: .test-cache-local
-  rules:
-    - if: $CI_PARENT_PIPELINE_SOURCE == "schedule"  # When schedueled (at night)
-    - if: $CI_PARENT_PIPELINE_SOURCE == "trigger"   # When triggered (manual triggers)
-    - if: '$CI_COMMIT_TAG != null'                  # When tags are set (releases)
-
-suite:vivado:vhdl:
-  extends: .test-cache-local-nightly
-  script:
-    - source /opt/tools/Xilinx/Vivado/2022.1/settings64.sh
-    - ./dist-newstyle/build/*/*/clash-testsuite-*/x/clash-testsuite/build/clash-testsuite/clash-testsuite -j$THREADS -p .VHDL --hide-successes --no-modelsim --no-ghdl --no-iverilog --no-verilator --no-symbiyosys
-  tags:
-    - local
-    - vivado-2022.1-standard
-
-suite:vivado:verilog:
-  extends: .test-cache-local-nightly
-  script:
-    - source /opt/tools/Xilinx/Vivado/2022.1/settings64.sh
-    - ./dist-newstyle/build/*/*/clash-testsuite-*/x/clash-testsuite/build/clash-testsuite/clash-testsuite -j$THREADS -p .Verilog --hide-successes --no-modelsim --no-ghdl --no-iverilog --no-verilator --no-symbiyosys
-  tags:
-    - local
-    - vivado-2022.1-standard
+# .test-cache-local-nightly:
+#   extends: .test-cache-local
+#   rules:
+#     - if: $CI_PARENT_PIPELINE_SOURCE == "schedule"  # When schedueled (at night)
+#     - if: $CI_PARENT_PIPELINE_SOURCE == "trigger"   # When triggered (manual triggers)
+#     - if: '$CI_COMMIT_TAG != null'                  # When tags are set (releases)
+
+# suite:vivado:vhdl:
+#   extends: .test-cache-local-nightly
+#   script:
+#     - source /opt/tools/Xilinx/Vivado/2022.1/settings64.sh
+#     - ./dist-newstyle/build/*/*/clash-testsuite-*/x/clash-testsuite/build/clash-testsuite/clash-testsuite -j$THREADS -p .VHDL --hide-successes --no-modelsim --no-ghdl --no-iverilog --no-verilator --no-symbiyosys
+#   tags:
+#     - local
+#     - vivado-2022.1-standard
+
+# suite:vivado:verilog:
+#   extends: .test-cache-local-nightly
+#   script:
+#     - source /opt/tools/Xilinx/Vivado/2022.1/settings64.sh
+#     - ./dist-newstyle/build/*/*/clash-testsuite-*/x/clash-testsuite/build/clash-testsuite/clash-testsuite -j$THREADS -p .Verilog --hide-successes --no-modelsim --no-ghdl --no-iverilog --no-verilator --no-symbiyosys
+#   tags:
+#     - local
+#     - vivado-2022.1-standard