Avoid tracking connections per host when there is no limit per host

[bdraco]

The BaseConnector always tracked connections per hosts even when the limit per host was disabled. All the book-keeping has overhead that we can avoid since in most cases there is no limit per host and no need to track connections per host.

BaseConnector._available_connections() was smart enough to skip checking the current connections if limit_per_hosts was not set, but the other areas still did all the book keeping even though it was ignored.

[codspeed-hq]

CodSpeed Performance Report

Merging #9756 will not alter performance

_{Comparing no_track_connection_no_limit (18e923a) with master (7c0b463)}

Summary

✅ 14 untouched benchmarks

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.67%. Comparing base (7c0b463) to head (18e923a).
Report is 1 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #9756   +/-   ##
=======================================
  Coverage   98.67%   98.67%           
=======================================
  Files         117      117           
  Lines       35893    35896    +3     
  Branches     4260     4263    +3     
=======================================
+ Hits        35417    35420    +3     
  Misses        320      320           
  Partials      156      156           

Flag	Coverage Δ
CI-GHA	98.56% <100.00%> (+<0.01%)	⬆️
OS-Linux	98.24% <100.00%> (+<0.01%)	⬆️
OS-Windows	96.01% <100.00%> (+<0.01%)	⬆️
OS-macOS	97.32% <100.00%> (+<0.01%)	⬆️
Py-3.10.11	97.16% <100.00%> (-0.01%)	⬇️
Py-3.10.15	97.77% <100.00%> (+0.05%)	⬆️
Py-3.11.10	97.77% <100.00%> (-0.06%)	⬇️
Py-3.11.9	97.22% <100.00%> (+<0.01%)	⬆️
Py-3.12.7	98.30% <100.00%> (+<0.01%)	⬆️
Py-3.13.0	98.30% <100.00%> (+0.05%)	⬆️
Py-3.9.13	97.08% <100.00%> (+<0.01%)	⬆️
Py-3.9.20	97.64% <100.00%> (-0.05%)	⬇️
Py-pypy7.3.16	97.25% <100.00%> (+<0.01%)	⬆️
VM-macos	97.32% <100.00%> (+<0.01%)	⬆️
VM-ubuntu	98.24% <100.00%> (+<0.01%)	⬆️
VM-windows	96.01% <100.00%> (+<0.01%)	⬆️

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[patchback]

Backport to 3.11: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 44d809f on top of patchback/backports/3.11/44d809f330aa249de582d8c3cdfd284fb4247483/pr-9756

Backporting merged PR #9756 into master

1. Ensure you have a local repo clone of your fork. Unless you cloned it
   from the upstream, this would be your origin remote.
2. Make sure you have an upstream repo added as a remote too. In these
   instructions you'll refer to it by the name upstream. If you don't
   have it, here's how you can add it:

   $ git remote add upstream https://github.com/aio-libs/aiohttp.git

3. Ensure you have the latest copy of upstream and prepare a branch
   that will hold the backported code:

   $ git fetch upstream
   $ git checkout -b patchback/backports/3.11/44d809f330aa249de582d8c3cdfd284fb4247483/pr-9756 upstream/3.11

4. Now, cherry-pick PR Avoid tracking connections per host when there is no limit per host #9756 contents into that branch:

   $ git cherry-pick -x 44d809f330aa249de582d8c3cdfd284fb4247483

   If it'll yell at you with something like fatal: Commit 44d809f330aa249de582d8c3cdfd284fb4247483 is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 44d809f330aa249de582d8c3cdfd284fb4247483

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Avoid tracking connections per host when there is no limit per host #9756 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.11/44d809f330aa249de582d8c3cdfd284fb4247483/pr-9756

7. Create a PR, ensure that the CI is green. If it's not — update it so that
   the tests and any other checks pass. This is it!
   Now relax and wait for the maintainers to process your pull request
   when they have some cycles to do reviews. Don't worry — they'll tell you if
   any improvements are necessary when the time comes!

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.