Improve performance of handling ports in the URL

[bdraco]

What do these changes do?

There were a few places were the port got parsed out of the underlying SplitResult object multiple times. Make sure they are all cached to avoid doing the same work over and over.

This solves a minor performance regression that was introduced with the port normalization in #1033

Are there changes in behavior for the user?

performance improvement

Related issue number

#1033

For reference, is_default_port from update_headers in aiohttp is showing significantly higher on the profile with recent yarl versions.

before

after

[codecov]

Codecov Report

Attention: Patch coverage is 91.66667% with 1 line in your changes missing coverage. Please review.

Project coverage is 93.02%. Comparing base (33ac3f1) to head (47b0d8f).
Report is 341 commits behind head on master.

Files with missing lines	Patch %	Lines
yarl/_url.py	91.66%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1081   +/-   ##
=======================================
  Coverage   93.01%   93.02%           
=======================================
  Files          31       31           
  Lines        4411     4414    +3     
  Branches      374      376    +2     
=======================================
+ Hits         4103     4106    +3     
  Misses        282      282           
  Partials       26       26           

Flag	Coverage Δ
CI-GHA	92.97% <91.66%> (+<0.01%)	⬆️
MyPy	26.39% <41.66%> (+0.04%)	⬆️
OS-Linux	99.22% <100.00%> (+<0.01%)	⬆️
OS-Windows	99.44% <100.00%> (+<0.01%)	⬆️
OS-macOS	98.90% <100.00%> (+<0.01%)	⬆️
Py-3.10.11	98.82% <100.00%> (+<0.01%)	⬆️
Py-3.10.14	99.07% <100.00%> (+<0.01%)	⬆️
Py-3.11.9	99.07% <100.00%> (+<0.01%)	⬆️
Py-3.12.5	99.07% <100.00%> (+<0.01%)	⬆️
Py-3.13.0-rc.1	99.07% <100.00%> (+<0.01%)	⬆️
Py-3.8.10	98.76% <100.00%> (+<0.01%)	⬆️
Py-3.8.18	99.02% <100.00%> (+<0.01%)	⬆️
Py-3.9.13	98.76% <100.00%> (+<0.01%)	⬆️
Py-3.9.19	99.02% <100.00%> (+<0.01%)	⬆️
Py-pypy7.3.11	99.19% <100.00%> (+<0.01%)	⬆️
Py-pypy7.3.16	99.22% <100.00%> (+<0.01%)	⬆️
VM-macos-latest	98.90% <100.00%> (+<0.01%)	⬆️
VM-ubuntu-latest	99.22% <100.00%> (+<0.01%)	⬆️
VM-windows-latest	99.44% <100.00%> (+<0.01%)	⬆️
pytest	99.22% <100.00%> (+<0.01%)	⬆️

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[bdraco]

The line is covered that codecov/project/tests-pytest and codecov/patch is complaining about