Fix how we check for OSIE.BaseURL:

[jacobweinstock]

Description

The object that gets returned from Kubernetes seems to always come back non-nil. So we need to also check if the string is empty.

Why is this needed

Fixes: #

How Has This Been Tested?

How are existing users impacted? What migration steps/scripts do we need?

Checklist:

I have:

• updated the documentation and/or roadmap (if required)
• added unit or e2e tests
• provided instructions on how to upgrade

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 56%. Comparing base (592aa2c) to head (ad251cd).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/ipxe/script/ipxe.go	0%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@         Coverage Diff         @@
##           main   #593   +/-   ##
===================================
  Coverage    56%    56%           
===================================
  Files        32     32           
  Lines      3624   3624           
===================================
  Hits       2056   2056           
  Misses     1495   1495           
  Partials     73     73           

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