fix(launch): remove extra colon from log prefix

[jamie-rasmussen]

Description

Removes an extra colon from log output.

Testing

How was this PR tested?

Checklist

• Include reference to internal ticket "Fixes WB-NNNN" and/or GitHub issue "Fixes #NNNN" (if applicable)
• Ensure PR title compliance with the conventional commits standards

[codecov]

Codecov Report

Merging #4450 (2472d52) into main (63fa971) will increase coverage by 0.01%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4450      +/-   ##
==========================================
+ Coverage   83.03%   83.04%   +0.01%     
==========================================
  Files         258      258              
  Lines       32871    32871              
==========================================
+ Hits        27294    27298       +4     
+ Misses       5577     5573       -4     

Flag	Coverage Δ
functest	56.87% <100.00%> (+0.19%)	⬆️
unittest	73.15% <100.00%> (-0.02%)	⬇️

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Impacted Files	Coverage Δ
wandb/sdk/launch/utils.py	92.59% <100.00%> (ø)
wandb/sdk/lib/sock_client.py	93.12% <0.00%> (-1.06%)	⬇️
wandb/sdk/lib/git.py	79.01% <0.00%> (ø)
wandb/sdk/wandb_run.py	90.97% <0.00%> (+0.05%)	⬆️
wandb/sdk/internal/system/system_info.py	91.55% <0.00%> (+3.24%)	⬆️