Change cow path selection variable from COWPATH to COW_PATH (#34063)

For consistency with other cow-related options, such as
`ANSIBLE_COW_SELECTION`, add an underscore to the new `ANSIBLE_COWPATH`
option.

lib/ansible/config/base.yml

@@ -56,11 +56,11 @@ ANSIBLE_NOCOWS:
   - {key: nocows, section: defaults}
   type: boolean
   yaml: {key: display.i_am_no_fun}
-ANSIBLE_COWPATH:
+ANSIBLE_COW_PATH:
   name: Set path to cowsay command
   default: null
   description: Specify a custom cowsay path or swap in your cowsay implementation of choice
-  env: [{name: ANSIBLE_COWPATH}]
+  env: [{name: ANSIBLE_COW_PATH}]
   ini:
   - {key: cowpath, section: defaults}
   type: string

lib/ansible/utils/display.py

@@ -101,8 +101,8 @@ class Display:
         if C.ANSIBLE_NOCOWS:
             return
 
-        if C.ANSIBLE_COWPATH:
-            self.b_cowsay = C.ANSIBLE_COWPATH
+        if C.ANSIBLE_COW_PATH:
+            self.b_cowsay = C.ANSIBLE_COW_PATH
         else:
             for b_cow_path in b_COW_PATHS:
                 if os.path.exists(b_cow_path):