GitLab CI: Switch back to explicit scheduling.

It looks like "extends" and YAML anchors don't work for scheduling
rules, at least for the way we're using them. Use explicit rules for
scheduled jobs.

.gitlab-ci.yml

@@ -28,7 +28,7 @@ variables:
   # Enable color output in CMake, Ninja, and other tools. https://bixense.com/clicolors/
   CLICOLOR_FORCE: 1
 
-# Scheduled builds additionally set WS_CI_SCHEDULE, which can be one of:
+# Scheduled builds additionally set SCHEDULE_TYPE, which can be one of:
 # - daily: Daily at 10:00 UTC
 # - coverity-visual-c++: Monday, Wednesday, & Friday at 12:00 UTC
 # - coverity-gcc: Sunday, Tuesday, Thursday & Saturday at 12:00 UTC
@@ -55,17 +55,11 @@ variables:
     - if: '$CI_PIPELINE_SOURCE == "merge_request_event" && $CI_PROJECT_URL =~ /.*gitlab.com\/wireshark\/wireshark/'
       when: always
 # Daily jobs
-.if-daily-schedule:
-  # According to the GitLab docs, specifying "rules" is perferred over "only",
-  # but this doesn't get triggered.
-  # rules:
-  #   - if: '$CI_PIPELINE_SOURCE == "schedule" && $WS_CI_SCHEDULE == "daily"'
-  #     when: always
-  only:
-    refs:
-      - schedules
-    variables:
-      - $SCHEDULE_TYPE == "daily"
+# Schedules don't appear to work with "extends" or YAML anchors, unfortunately.
+# .if-daily-schedule
+#   rules:
+#     - if: '$CI_PIPELINE_SOURCE == "schedule" && $SCHEDULE_TYPE == "daily"'
+#       when: always
 
 .build:
   stage: build
@@ -322,9 +316,11 @@ docbook:
 
 # Build all doxygen docs
 doxygen_all:
-  extends: .if-daily-schedule
-  stage: build
   image: wireshark/wireshark-ubuntu-dev
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "schedule" && $SCHEDULE_TYPE == "daily"'
+      when: always
+  stage: build
   script:
     - mkdir build
     - cd build
@@ -439,15 +435,10 @@ merge-req:windows:
 # Adapted from https://www.synopsys.com/blogs/software-security/integrating-coverity-scan-with-gitlab-ci/
 # and https://gitlab.gnome.org/GNOME/glib/-/blob/8f57a5b9/.gitlab-ci.yml#L481
 coverity-gcc:
-  # rules:
-  #   - if: '$CI_PIPELINE_SOURCE == "schedule" && $WS_CI_SCHEDULE == "coverity-gcc"'
-  #     when: always
-  only:
-    refs:
-      - schedules
-    variables:
-      - $WS_CI_SCHEDULE == "coverity-gcc"
   image: wireshark/wireshark-ubuntu-dev
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "schedule" && $SCHEDULE_TYPE == "coverity-gcc"'
+      when: always
   stage: analysis
   needs: []
   variables:
@@ -471,15 +462,10 @@ coverity-gcc:
       - build/cov-int.tar.gz
 
 coverity-visual-c++:
-  # rules:
-  #   - if: '$CI_PIPELINE_SOURCE == "schedule" && $WS_CI_SCHEDULE == "coverity-visual-c++"'
-  #     when: always
-  only:
-    refs:
-      - schedules
-    variables:
-      - $WS_CI_SCHEDULE == "coverity-visual-c++"
   extends: .build-windows
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "schedule" && $SCHEDULE_TYPE == "coverity-visual-c++"'
+      when: always
   tags:
     - wireshark-windows-merge-req
   stage: analysis
@@ -499,8 +485,10 @@ coverity-visual-c++:
       - build/cov-int.zip
 
 clang-scan-build:
-  extends: .if-daily-schedule
   image: wireshark/wireshark-ubuntu-dev
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "schedule" && $SCHEDULE_TYPE == "daily"'
+      when: always
   stage: analysis
   needs: []
   variables:
@@ -528,7 +516,7 @@ build:windows-vs-code-analysis:
     - wireshark-windows-dev
   rules:
     # The wireshark-windows-* tags are only available in wireshark/wireshark.
-    - if: '$CI_PIPELINE_SOURCE == "schedule" && $WS_CI_SCHEDULE == "daily" && $CI_PROJECT_URL =~ /.*gitlab.com\/wireshark\/wireshark/'
+    - if: '$CI_PIPELINE_SOURCE == "schedule" && $SCHEDULE_TYPE == "daily" && $CI_PROJECT_URL =~ /.*gitlab.com\/wireshark\/wireshark/'
       when: always
   script:
     - $env:caexcludepath = "C:\Qt;$env:INCLUDE"
@@ -536,9 +524,10 @@ build:windows-vs-code-analysis:
     - msbuild /verbosity:minimal "/consoleloggerparameters:PerformanceSummary;NoSummary" /maxcpucount:2 Wireshark.sln
 
 sloccount:
-  extends:
-    - .build-ubuntu
-    - .if-daily-schedule
+  extends: .build-ubuntu
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "schedule" && $SCHEDULE_TYPE == "daily"'
+      when: always
   stage: analysis
   variables:
     SLOC_OUT: sloccount.txt