feat(instance): add fetch-keys to ssh commands

[Mia-Cross]

Closes #2356

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 33.75000% with 53 lines in your changes missing coverage. Please review.

Project coverage is 55.10%. Comparing base (5bf53e0) to head (38d5db9).
Report is 571 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/namespaces/instance/v1/custom_ssh_key.go	32.91%	52 Missing and 1 partial ⚠️

❗ There is a different number of reports uploaded between BASE (5bf53e0) and HEAD (38d5db9). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (5bf53e0)	HEAD (38d5db9)
	2	1

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #4622       +/-   ##
===========================================
- Coverage   75.45%   55.10%   -20.35%     
===========================================
  Files         202      308      +106     
  Lines       44323    70040    +25717     
===========================================
+ Hits        33444    38597     +5153     
- Misses       9653    30045    +20392     
- Partials     1226     1398      +172     

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