fix(instance_server): allow updating root_volume size for non l_ssd

[Codelax]

Missed from #2745

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 70.00000% with 6 lines in your changes missing coverage. Please review.

Project coverage is 67.75%. Comparing base (fe86049) to head (6d0d70f).
Report is 240 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/services/instance/server.go	70.00%	4 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2842      +/-   ##
==========================================
- Coverage   71.43%   67.75%   -3.69%     
==========================================
  Files         277      339      +62     
  Lines       35875    40109    +4234     
==========================================
+ Hits        25628    27174    +1546     
- Misses       8028    10621    +2593     
- Partials     2219     2314      +95     

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