Decrease device auto timeout to 15 seconds from 30

[hardillb]

part of #4832

Description

reduces the time the device agent will continue to send logs in the background if a single user navigates away from the logs page. This should make for a better experience of returning to the page and seeing log history.

Related Issue(s)

Checklist

• I have read the contribution guidelines
• Suitable unit/system level tests have been added and they pass
• Documentation has been updated
  • Upgrade instructions
  • Configuration details
  • Concepts
• Changes flowforge.yml?
  • Issue/PR raised on FlowFuse/helm to update ConfigMap Template
  • Issue/PR raised on FlowFuse/CloudProject to update values for Staging/Production

Labels

• Includes a DB migration? -> add the area:migration label

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 78.64%. Comparing base (bdf5dae) to head (d6cd220).
Report is 12 commits behind head on main.

Files with missing lines	Patch %	Lines
forge/comms/devices.js	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4932      +/-   ##
==========================================
+ Coverage   78.63%   78.64%   +0.01%     
==========================================
  Files         324      324              
  Lines       15265    15265              
  Branches     3507     3507              
==========================================
+ Hits        12003    12005       +2     
+ Misses       3262     3260       -2     

Flag	Coverage Δ
backend	78.64% <0.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.