[3.11] Remove unused backwards compatibility code in web_urldispatcher for old yarl versions

[bdraco]

What do these changes do?

#9068 (comment)

There are some checks that only existed in 3.11/3.10

As the yarl requirement is not increasing for 3.10, we will keep these shims

yarl >=3.11 is now required for aiohttp 3.11 via #9082

Are there changes in behavior for the user?

no

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.30%. Comparing base (64c36e2) to head (2fb992a).
Report is 3164 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9084      +/-   ##
==========================================
+ Coverage   97.69%   98.30%   +0.60%     
==========================================
  Files         108      107       -1     
  Lines       34169    34415     +246     
  Branches     4064     4080      +16     
==========================================
+ Hits        33383    33831     +448     
+ Misses        587      412     -175     
+ Partials      199      172      -27     

Flag	Coverage Δ
CI-GHA	98.19% <100.00%> (+0.60%)	⬆️
OS-Linux	97.86% <100.00%> (+0.58%)	⬆️
OS-Windows	96.27% <100.00%> (+1.47%)	⬆️
OS-macOS	97.54% <100.00%> (+0.60%)	⬆️
Py-3.10.11	97.63% <100.00%> (+0.61%)	⬆️
Py-3.10.14	97.57% <100.00%> (+0.59%)	⬆️
Py-3.11.9	97.80% <100.00%> (+0.58%)	⬆️
Py-3.12.4	?
Py-3.12.5	97.91% <100.00%> (?)
Py-3.8.10	?
Py-3.8.18	?
Py-3.9.13	97.52% <100.00%> (+0.59%)	⬆️
Py-3.9.19	97.46% <100.00%> (+0.57%)	⬆️
Py-pypy7.3.16	97.07% <100.00%> (+0.59%)	⬆️
VM-macos	97.54% <100.00%> (+0.60%)	⬆️
VM-ubuntu	97.86% <100.00%> (+0.58%)	⬆️
VM-windows	96.27% <100.00%> (+1.47%)	⬆️

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