Followup for enforcing manual agent install restrictions in gitops

[jkatz01]

Related issue: Resolves #40412

Testing

• Added/updated automated tests

• Where appropriate, automated tests simulate multiple hosts and test for host isolation (updates to one hosts's records do not affect another)

• QA'd all new/changed functionality manually

• Individually or together setting vpp, software installers, or fleet maintained apps will send the correct error now when applied to no team with manual_agent_install enabled.

[codecov]

Codecov Report

❌ Patch coverage is 53.84615% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 66.27%. Comparing base (adeec0a) to head (e4b3eb4).
⚠️ Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
ee/server/service/software_installers.go	53.84%	4 Missing and 2 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #40503   +/-   ##
=======================================
  Coverage   66.26%   66.27%           
=======================================
  Files        2461     2461           
  Lines      197427   197435    +8     
  Branches     8655     8655           
=======================================
+ Hits       130832   130845   +13     
+ Misses      54749    54742    -7     
- Partials    11846    11848    +2     

Flag	Coverage Δ
backend	68.14% <53.84%> (+<0.01%)	⬆️

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