Fleet UI: Host status dropdown styling fixes

[RachelElysia]

Issue

Cerra #21129

Description

• Remove max-height causing the dropdown options to be cut off
• Looks like the centering bug was already fixed (likely global fix happened with work on software dropdown options)

Note: Also removed some related sandbox code (context: sandbox is a deprecated feature we had for users to trial premium and it's been a long run of trying to remove all related code)

Screenshot of 1 of the fixes

Checklist for submitter

If some of the following don't apply, delete the relevant line.

• Manual QA for all new/changed functionality

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.22%. Comparing base (b14f7fa) to head (92179b2).
Report is 21 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #22314   +/-   ##
=======================================
  Coverage   65.22%   65.22%           
=======================================
  Files        1496     1496           
  Lines      117247   117247           
  Branches     3563     3514   -49     
=======================================
  Hits        76474    76474           
- Misses      33636    33637    +1     
+ Partials     7137     7136    -1     

Flag	Coverage Δ
frontend	52.35% <ø> (ø)

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