Revert "feat: process variables in include vars (#2113)"

This reverts commit f0414f162d.

testdata/include_with_vars/Taskfile.yml

@@ -1,23 +1,16 @@
 version: "3"
 
-vars:
-  VAR_1: included4-var1
-
 includes:
   included1:
-    taskfile: include/Taskfile.include.yml
+    taskfile: include/Taskfile.include1.yml
     vars:
       VAR_1: included1-var1
   included2:
-    taskfile: include/Taskfile.include.yml
+    taskfile: include/Taskfile.include2.yml
     vars:
       VAR_1: included2-var1
   included3:
-    taskfile: include/Taskfile.include.yml
-  included4:
-    taskfile: include/Taskfile.include.yml
-    vars:
-      VAR_1: "{{.VAR_1}}"
+    taskfile: include/Taskfile.include3.yml
 
 tasks:
   task1:
@@ -25,4 +18,3 @@ tasks:
       - task: included1:task1
       - task: included2:task1
       - task: included3:task1
-      - task: included4:task1

testdata/include_with_vars/include/Taskfile.include2.yml

@@ -0,0 +1,11 @@
+version: "3"
+
+vars:
+  VAR_1: '{{.VAR_1 | default "included-default-var1"}}'
+  VAR_2: '{{.VAR_2 | default "included-default-var2"}}'
+
+tasks:
+  task1:
+    cmds:
+      - echo "VAR_1 is {{.VAR_1}}"
+      - echo "VAR_2 is {{.VAR_2}}"

testdata/include_with_vars/include/Taskfile.include3.yml

@@ -0,0 +1,11 @@
+version: "3"
+
+vars:
+  VAR_1: '{{.VAR_1 | default "included-default-var1"}}'
+  VAR_2: '{{.VAR_2 | default "included-default-var2"}}'
+
+tasks:
+  task1:
+    cmds:
+      - echo "VAR_1 is {{.VAR_1}}"
+      - echo "VAR_2 is {{.VAR_2}}"