many: update recovery boot assets

[alfonsosanchezbeato]

Update recovery boot assets when a new edition is shipped by snapd. This allows updating

1. The grub configuration file in the seed partition
2. The static bits of the kernel command line used for recovery/install/factory reset

[alfonsosanchezbeato]

Creating as draft until it is clear that spread tests are ok with this change.

[codecov-commenter]

Codecov Report

Merging #13331 (4bae60b) into master (4dba256) will increase coverage by 0.00%. Report is 6 commits behind head on master. The diff coverage is 88.20%.

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@@           Coverage Diff            @@
##           master   #13331    +/-   ##
========================================
  Coverage   78.80%   78.81%            
========================================
  Files        1019     1019            
  Lines      126571   126676   +105     
========================================
+ Hits        99742    99834    +92     
- Misses      20591    20603    +12     
- Partials     6238     6239     +1     

Flag	Coverage Δ
unittests	78.81% <88.20%> (+<0.01%)	:arrow_up:

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

Files	Coverage Δ
boot/seal.go	74.54% <100.00%> (ø)
bootloader/assets/grub.go	100.00% <100.00%> (ø)
daemon/api_sideload_n_try.go	81.07% <100.00%> (ø)
gadget/update.go	85.62% <100.00%> (+0.31%)	:arrow_up:
overlord/devicestate/devicestate.go	82.04% <100.00%> (+0.05%)	:arrow_up:
overlord/devicestate/firstboot.go	89.45% <100.00%> (+0.15%)	:arrow_up:
overlord/devicestate/handlers_bootconfig.go	66.66% <ø> (ø)
overlord/snapstate/handlers.go	68.58% <100.00%> (ø)
overlord/snapstate/refreshhints.go	79.89% <100.00%> (ø)
overlord/snapstate/snapstate.go	84.28% <100.00%> (+0.08%)	:arrow_up:
... and 8 more

... and 2 files with indirect coverage changes

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[alfonsosanchezbeato]

re-visit once related boot asset changes from Valentin have landed