Fixing role dependency chain creation

The dep chain for roles created during the compile step had bugs, in
which the dep chain was overwriten and the original tasks in the role
were not assigned a dep chain. This lead to problems in determining
whether roles had already run when in a "diamond" structure, and in
some cases roles were not correctly getting variables from parents.

Fixes #14046

test/integration/roles/test_var_precedence_dep/tasks/main.yml

@@ -7,7 +7,7 @@
 - assert:
     that:
       - 'extra_var == "extra_var"'
-      - 'param_var == "param_var"'
+      - 'param_var == "param_var_role1"'
       - 'vars_var == "vars_var"'
       - 'vars_files_var == "vars_files_var"'
       - 'vars_files_var_role == "vars_files_var_dep"'