Merge #259

259: Add allocation percentage change info string r=valeriabarra a=valeriabarra

## Purpose 
This quick PR improves the allocation percentage change info string. I personally find the percentage increase/decrease easier to understand than the delta.


## Content
- Updated the ``@info`` string showing an allocation percentage increase or decrease 


Review checklist

I have:
- followed the codebase contribution guide: https://clima.github.io/ClimateMachine.jl/latest/Contributing/
- followed the style guide: https://clima.github.io/ClimateMachine.jl/latest/DevDocs/CodeStyle/
- followed the documentation policy: https://github.com/CliMA/policies/wiki/Documentation-Policy
- checked that this PR does not duplicate an open PR.

In the Content, I have included 
- relevant unit tests, and integration tests, 
- appropriate docstrings on all functions, structs, and modules, and included relevant documentation.

- [x] I have read and checked the items on the review checklist.


Co-authored-by: Valeria Barra <[email protected]>

perf/flame.jl

@@ -84,7 +84,7 @@ end
 
 # We're grouping allocation tests here for convenience.
 
-buffer = 1 # increase slightly for (nondeterministic) threaded runs
+buffer = 1.2 # increase slightly for (nondeterministic) threaded runs
 
 # profile the coupling loop
 allocs = @allocated step_coupler!(cs, n_samples)
@@ -98,6 +98,12 @@ end
 
 Δallocs = allocs / allocs_limit[run_name]
 @info "Allocation change (allocs/allocs_limit): $Δallocs"
+percent_alloc_change = (1 - Δallocs) * 100
+if percent_alloc_change ≥ 0
+    @info "Allocations improved by: $percent_alloc_change %"
+else
+    @info "Allocations worsened by: $percent_alloc_change %"
+end
 
 @testset "Allocations limit" begin
     @test allocs ≤ allocs_limit[run_name]