fix(pipeline): always set local to true for validate local

[ecrupper]

We've got the necessary logic packed in to the compiler code here to have ValidateLocal always use a compiler engine with local set to true.

• If the template is of type file and the engine is local, then it will fetch from the filesystem.
• If the template is of type github and the engine is local, it will fallthrough and attempt to fetch using user provided credentials
• If the template is being replaced using --template-file it will source those from the filesystem like usual.

Closes go-vela/community#916

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (45bc445) 82.32% compared to head (693d302) 82.34%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #534      +/-   ##
==========================================
+ Coverage   82.32%   82.34%   +0.02%     
==========================================
  Files         147      147              
  Lines        3620     3619       -1     
==========================================
  Hits         2980     2980              
+ Misses        473      472       -1     
  Partials      167      167              

Files	Coverage Δ
command/pipeline/validate.go	65.71% <100.00%> (+1.82%)	⬆️

[KellyMerrick]

lgtm