gh-132372: Speed up logging.config existing logger handling

[esadomer]

gh-132372

This speeds up logging.config.fileConfig() and logging.config.dictConfig() when they need to handle many existing loggers while disable_existing_loggers is active.

The old code kept the existing logger names in a sorted list, but still used repeated list membership, index(), tail scans, and remove() calls for every configured logger. This keeps the sorted list for child logger ordering, uses a set for membership/removal tracking, and uses bisect_left() to jump directly to the dotted child logger range.

It also batches the manager-wide logging cache clear when preserving child loggers. Previously each preserved child called Logger.setLevel(NOTSET), and each call cleared the cache for every logger.

Validation:

• PCbuild\build.bat -d -p x64
• PCbuild\amd64\python_d.exe -m test test_logging -j0
• PCbuild\amd64\python_d.exe Tools\patchcheck\patchcheck.py
• git diff --check

Benchmark:

Loaded upstream/main:Lib/logging/config.py and the patched Lib/logging/config.py into the same Python 3.12.8 release interpreter, then timed only the dictConfig() call while resetting identical existing logger state outside the timer.

old n=100  mean=   5.742 ms stdev=  0.160 ms
new n=100  mean=   2.255 ms stdev=  0.051 ms
speedup n=100: 2.55x

old n=500  mean= 133.837 ms stdev=  6.404 ms
new n=500  mean=  42.336 ms stdev=  0.586 ms
speedup n=500: 3.16x

old n=1000 mean= 537.785 ms stdev= 44.765 ms
new n=1000 mean= 170.014 ms stdev=  2.729 ms
speedup n=1000: 3.16x

[eendebakpt]

The performance increase is moderate, but the PR reduces code duplication so I am +1.

@esadomer On your benchmark I could get a much larger speedud with this small commit 2b9ce22 (on top of your work). I have not fully tested this, but the speedup is > 5x. If you are interested you could test it further and pull into your branch.