Change Imagery positional freshness label from 'POS' to 'ROV'

[charlesh88]

Closes #7404. Note that this is critical in order to be in parity with the same display in VERVE.

Describe your changes:

Title says it all.

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Author Checklist

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (1148644) 55.97% compared to head (be94b3d) 56.01%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7409      +/-   ##
==========================================
+ Coverage   55.97%   56.01%   +0.04%     
==========================================
  Files         660      660              
  Lines       26282    26282              
  Branches     2550     2550              
==========================================
+ Hits        14711    14723      +12     
+ Misses      10860    10848      -12     
  Partials      711      711              

Flag	Coverage Δ
e2e-full	41.97% <ø> (ø)
e2e-stable	60.22% <ø> (+0.15%)	⬆️
unit	48.92% <ø> (-0.01%)	⬇️

Files	Coverage Δ
src/plugins/imagery/components/ImageryView.vue	40.19% <ø> (ø)

... and 6 files with indirect coverage changes

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