Fix incorrect 'start-failed' notifications

[knolleary]

Description

When starting a suspended instance, I was getting a 'Start Failed' notification even though it had succeeded.

This fixes that. The API returns a proper status object, whereas the code was treating any non-blank response as an error.

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 flowforge/helm to update ConfigMap Template
  • Issue/PR raised on flowforge/CloudProject to update values for Staging/Production

Labels

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

[codecov]

Codecov Report

Merging #2505 (32e149b) into main (0edbce6) will decrease coverage by 72.85%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main   #2505       +/-   ##
==========================================
- Coverage   74.39%   1.55%   -72.85%     
==========================================
  Files         224     489      +265     
  Lines        8850   17129     +8279     
  Branches     1822    3968     +2146     
==========================================
- Hits         6584     266     -6318     
- Misses       2266   16863    +14597     

Flag	Coverage Δ
backend	?
frontend	1.55% <0.00%> (?)

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

Impacted Files	Coverage Δ
frontend/src/pages/application/index.vue	0.00% <0.00%> (ø)
frontend/src/pages/instance/index.vue	0.00% <0.00%> (ø)

... and 440 files with indirect coverage changes

[Pezmc]

Were you able to track down when this API changed?

[knolleary]

Part of the swagger doc work in 1.9