lint: use consistent short slice creation syntax

[NathanBaulch]

There are a few different patterns used to create slices. This PR makes them all consistent.
This is something I noticed whilst building the it subpackage.

[codecov]

Codecov Report

❌ Patch coverage is 93.33333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 94.22%. Comparing base (4e2c33e) to head (d45d138).

Files with missing lines	Patch %	Lines
slice.go	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #729      +/-   ##
==========================================
+ Coverage   94.19%   94.22%   +0.03%     
==========================================
  Files          18       18              
  Lines        2806     2806              
==========================================
+ Hits         2643     2644       +1     
+ Misses        149      148       -1     
  Partials       14       14              

Flag	Coverage Δ
unittests	94.22% <93.33%> (+0.03%)	⬆️

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[samber]

There is actually a small difference between var a []A and a := []A{}. When you compare a to nil, the first case will output true.

https://go.dev/play/p/ZT1csskjjK_b

[NathanBaulch]

I'm aware of that but have yet to find a real-world situation (other than edge cases using reflection) where this was an issue.
As usual, I advocate for consistency. If we want to avoid nil slices then we should do it everywhere and validate with unit tests.