ER: refactor the existing workflow that posts a message on issues when someone assigns.

### Dependency
- #4944

### Emergent Requirement - Problem
The message our bot sends when people self assign issues, needs to be slightly different for prework issues so it doesn't have inaccurate info.

### Issue you discovered this emergent requirement in
- any assigned issue
- any assigned prework

### Date discovered
2023-02-19

### Did you have to do something temporarily
- [ ] YES
- [x] NO

### Who was involved
@experimentsinhonesty

### What happens if this is not addressed
people get confused.

### Resources
- workflow: https://github.com/hackforla/website/blob/gh-pages/.github/workflows/issue-trigger.yml
- JS file: https://github.com/hackforla/website/blob/gh-pages/github-actions/trigger-issue/add-preliminary-comment/preliminary-update-comment.js
- Source file for the message: https://github.com/hackforla/website/blob/gh-pages/github-actions/trigger-issue/add-preliminary-comment/preliminary-update.md
text of message

Hi @${issueAssignee}, thank you for taking up this issue! Hfla appreciates you :)

Do let fellow developers know about your:-
i. **Availability:** (When are you available to work on the issue/answer questions other programmers might have about your issue?)
ii. **ETA:** (When do you expect this issue to be completed?)

You're awesome!

P.S. - You may not take up another issue until this issue gets merged (or closed). Thanks again :)

### Recommended Action Items
- [x] Make a new issue
- [ ] Discuss with team
- [ ] Let a Team Lead know

### Potential solutions [draft]

#### Draft of new message to be sent on preworks instead of the current message.
```
Hi @${issueAssignee}, congrats for joining the Hack for LA website team. Hfla appreciates you :)

Let us know your availability to work through the steps in the prework
i. **Availability:** (When are you available to work on the prework and setting up your dev environment?)
ii. **ETA:** (When do you expect this issue to be completed?)

You're awesome!

P.S. - If you have issues setting up your dev enviorment or getting access to any resources, please leave a comment in this issue and then copy the link to the comment, into the #hfla-site Slack channel
```