[Prism] Implement jobservices.Server Cancel

[damondouglas]

This PR addresses #29669 via implementation of jobservices.Server Cancel method.

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[codecov]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (a221f98) 38.42% compared to head (0763a0c) 38.44%.
Report is 11 commits behind head on master.

Files	Patch %	Lines
sdks/go/pkg/beam/runners/prism/internal/execute.go	0.00%	4 Missing and 1 partial ⚠️
...pkg/beam/runners/prism/internal/jobservices/job.go	50.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #30178      +/-   ##
==========================================
+ Coverage   38.42%   38.44%   +0.02%     
==========================================
  Files         697      697              
  Lines      102215   102244      +29     
==========================================
+ Hits        39272    39305      +33     
+ Misses      61315    61309       -6     
- Partials     1628     1630       +2     

Flag	Coverage Δ
go	54.22% <75.86%> (+0.04%)	⬆️

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[riteshghorse]

LGTM, thanks!

[lostluck]

I'm late, but also LGTM.