more isolated task execution tweaking

* set a more reasonable default `AWX_ISOLATED_CHECK_INTERVAL`
* make manual cancellation work for high values of
  `AWX_ISOLATED_CHECK_INTERVAL`
* remove the `/tmp/ansible_tower/jobs/` symlink directory

see: #6616

awx/playbooks/run_isolated.yml

@@ -4,7 +4,6 @@
 # src: /tmp/some/path/private_data_dir
 # dest: /tmp/some/path/
 # proot_temp_dir: /tmp/some/path
-# job_id: <pk>
 
 - hosts: all
   gather_facts: false
@@ -26,20 +25,14 @@
         src: "{{src}}"
         dest: "{{dest}}"
 
-    - name: create a directory for running jobs
-      file: path=/tmp/ansible_tower/jobs state=directory mode=0700
-
-    - name: create symlink keyed by job ID
-      file: src="{{src}}" dest="/tmp/ansible_tower/jobs/{{job_id}}" state=link
-
     - name: create a named pipe for secret environment data
-      command: "mkfifo /tmp/ansible_tower/jobs/{{job_id}}/env"
+      command: "mkfifo {{src}}/env"
 
     - name: spawn the playbook
-      command: "tower-expect start {{job_id}}"
+      command: "tower-expect start {{src}}"
 
     - name: write the secret environment data
       mkfifo:
         content: "{{secret}}"
-        path: "/tmp/ansible_tower/jobs/{{job_id}}/env"
+        path: "{{src}}/env"
       no_log: True