text: Title: "local-shell-script" does not work on read only file systems
  Body: ## SUMMARY
  
  While using the action runner type "local-shell-script", the action always try to set execute permission for the action script before the execution. 
  
  For example, action runner logs for the core.sendmail action 
  
  ```
  2022-03-09 07:02:06,866 INFO [-] Executing action via LocalRunner: dcc6c28d-5674-4cc2-9174-ca6c1e7b23a3
  2022-03-09 07:02:06,866 INFO [-] [Action info] name: sendmail, Id: 622850eead44b087ebe77063, command: chmod +x /opt/stackstorm/packs/core/actions/send_mail/send_mail ; sudo -E -H -u stanley -- bash -c '/opt/stackstorm/packs/core/actions/send_mail/send_mail None stanley test@testmail.com '"'"'validate st2 local-shell-script runner'"'"' 1 text/html '"'"'validate st2 local-shell-script runner content'"'"' '"'"''"'"'', user: stanley, sudo: False
  ```
  This "chmod +x " operation cause failure when you are using stackstorm-ha helm chart based deployment with an immutable file system for packs. 
  
  https://docs.stackstorm.com/install/k8s_ha.html#method-1-st2packs-images-the-default 
  
  For example, my custom pack deployed via the st2pack image method fails to run the action since the "chmod +x" instruction cannot be executed on a read-only file system. 
  
  ```
  {
    "failed": true,
    "succeeded": false,
    "return_code": 1,
    "stdout": "",
    "stderr": "chmod: changing permissions of '/opt/stackstorm/packs/workflow/actions/verify_env.sh': Read-only file system"
  }
  ```
  **Logs:**
  
  ```
  2022-03-08 13:06:39,736 INFO [-] Executing action via LocalRunner: a2bdfba5-682b-47b2-9485-4241b94501cf
  2022-03-08 13:06:39,737 INFO [-] [Action info] name: verify_env, Id: 622754dfb56ccf38de50a292, command: chmod +x /opt/stackstorm/packs/workflow/actions/verify_env.sh ; sudo -E -H -u stanley -- bash -c '/opt/stackstorm/packs/workflow/actions/verify_env.sh '"'"'MY_ARGUMENTS_HERE'"'"'', user: stanley, sudo: False
  2022-03-08 13:06:39,748 INFO [-] [622754de749089f0a983f6c3] Action execution "622754dfb56ccf38de50a293" for task "verify_env" is updated and in "running" state.
  2022-03-08 13:06:39,848 INFO [-] [622754de749089f0a983f6c3] Action execution "622754dfb56ccf38de50a293" for task "verify_env" is updated and in "failed" state.
  2022-03-08 13:06:39,855 INFO [-] Found 0 rules defined for trigger core.st2.generic.actiontrigger
  2022-03-08 13:06:39,856 INFO [-] No matching rules found for trigger instance 622754dfe3850ebc7fd8d8c8.
  ```
  
  I guess it's failing because of the condition mentioned here below for the local shell script runner. 
  
  https://github.com/StackStorm/st2/blob/master/contrib/runners/local_runner/local_runner/base.py#L121
  
  ### STACKSTORM VERSION
  
  ```
  root@m1-staging-st2actionrunner-6664d699c-55z5t:/opt/stackstorm# st2 --version
  st2 3.6.0, on Python 3.6.9
  ```
  
  ### OS, environment, install method
  
  stackstorm-ha helm deployed k8s environment running on EKS cluster 
  
  ### Steps to reproduce the problem
  
  Follow the method mentioned here to deploy a custom st2 pack image and try to execute the action with runner type as "local-shell-script"
  
  https://docs.stackstorm.com/install/k8s_ha.html#method-1-st2packs-images-the-default
  
  ### Expected Results
  
  The action executes fine without a "chmod: changing permissions of '/opt/stackstorm/packs/custom-pack/actions/custom-script.sh': Read-only file system" failure and return the results.
  
  ### Actual Results
  
  ```
  {
    "failed": true,
    "succeeded": false,
    "return_code": 1,
    "stdout": "",
    "stderr": "chmod: changing permissions of '/opt/stackstorm/packs/workflow/actions/verify_env.sh': Read-only file system"
  }
  ```
  
  Thanks!
  