Remove unnecessary expression and move lower bound of flow variable from src/constraints/capacity.jl

[abelsiqueira]

• Remove unnecessary accumulated_investment_limit expression
• Move lower bound of flow variable from capacity.jl to variable creation

Related to #961

[github-actions]

Benchmark Results

	b34be57...	763bb82...	b34be57.../763bb82686e971...
energy_problem/create_model	40.5 ± 1.5 s	42.6 ± 0.96 s	0.952
energy_problem/input_and_constructor	16.3 ± 0.084 s	16.5 ± 0.26 s	0.989
time_to_load	3.97 ± 0.017 s	4.11 ± 0.076 s	0.965

	b34be57...	763bb82...	b34be57.../763bb82686e971...
energy_problem/create_model	0.614 G allocs: 21.3 GB	0.603 G allocs: 21.6 GB	0.987
energy_problem/input_and_constructor	0.0436 G allocs: 1.71 GB	0.0436 G allocs: 1.71 GB	1
time_to_load	0.159 k allocs: 11.2 kB	0.159 k allocs: 11.2 kB	1

Benchmark Plots

A plot of the benchmark results have been uploaded as an artifact to the workflow run for this PR.
Go to "Actions"->"Benchmark a pull request"->[the most recent run]->"Artifacts" (at the bottom).

[codecov]

Codecov Report

Attention: Patch coverage is 87.50000% with 1 line in your changes missing coverage. Please review.

Project coverage is 94.84%. Comparing base (606766e) to head (763bb82).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/variables/flows.jl	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #976      +/-   ##
==========================================
- Coverage   94.93%   94.84%   -0.10%     
==========================================
  Files          29       29              
  Lines        1066     1066              
==========================================
- Hits         1012     1011       -1     
- Misses         54       55       +1     

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[datejada]

Reviewed during online meeting