[BUG] deploy.sh update is clobbering the logstash writer password

[tfriesen]

Describe the issue
If I select autoupdates when install logstash, the update script will eventually lose the logstash writer password, somehow. I suspect the sed command in deploy.sh is weak and needs some improvement, but am unsure of the exact cause.

To Reproduce
Steps to reproduce the behavior:

1. deploy.sh install
2. select 'y' when prompted to enable auto-updated
3. wait for the update script to run (alternatively, manually run it (untested) )
4. run docker logs lme_logstash... and see 401 errors connecting to the ES stack
5. check logstash.conf and see that it contains 'insertpasswordhere'

Expected behavior
Update retains the logstash writer passwords

Linux Server (please complete the following information):

• Docker: 19.03.5
• Docker compose stack file version: 0.2
• Linux: Ubuntu 18.04.4 LTS
• Logstash Version #LME logstash config V0.2

Additional context
Fresh install, no other issues