Try include direct without trigger

.gitlab/main.gitlab-ci.yml

-stages:
-  - main
+# stages:
+#   - main
 
-conan-el6-gcc44:
-  stage: main
-  trigger: 
-    include: .gitlab/conan-el6-gcc44.gitlab-ci.yml
-    strategy: depend
+# conan-el6-gcc44:
+#   stage: main
+#   trigger: 
+#     include: .gitlab/conan-el6-gcc44.gitlab-ci.yml
+#     strategy: depend
 
-conan-el6-gcc44-x86:
-  stage: main
-  trigger: 
-    include: .gitlab/conan-el6-gcc44-x86.gitlab-ci.yml
-    strategy: depend
+# conan-el6-gcc44-x86:
+#   stage: main
+#   trigger: 
+#     include: .gitlab/conan-el6-gcc44-x86.gitlab-ci.yml
+#     strategy: depend
 
-conan-el7-gcc48:
-  stage: main
-  trigger: 
-    include: .gitlab/conan-el7-gcc48.gitlab-ci.yml
-    strategy: depend
+# conan-el7-gcc48:
+#   stage: main
+#   trigger: 
+#     include: .gitlab/conan-el7-gcc48.gitlab-ci.yml
+#     strategy: depend
 
-conan-el7-gcc48-x86:
-  stage: main
-  trigger: 
-    include: .gitlab/conan-el7-gcc48-x86.gitlab-ci.yml
-    strategy: depend
+# conan-el7-gcc48-x86:
+#   stage: main
+#   trigger: 
+#     include: .gitlab/conan-el7-gcc48-x86.gitlab-ci.yml
+#     strategy: depend
+
+include: 
+  - .gitlab/conan-el6-gcc44.gitlab-ci.yml
+  - .gitlab/conan-el6-gcc44-x86.gitlab-ci.yml
+  - .gitlab/conan-el7-gcc48.gitlab-ci.yml
+  - .gitlab/conan-el7-gcc48-x86.gitlab-ci.yml
\ No newline at end of file