opentelemetry-sdk: expose SynchronousMultiLogRecordProcessor and ConcurrentMultiLogRecordProcessor publicly (#5327)

* opentelemetry-test-utils: skip weaver tests on PyPy (#5176)

The weaver binary's gRPC C core crashes with SIGABRT (exit code -6) on
PyPy due to an epoll_wait EBADF error in ev_epoll1_linux.cc. This is a
known incompatibility between gRPC's epoll1 event engine and PyPy
subprocesses that cannot be fixed from the Python side.

Skip both weaver test classes on PyPy, consistent with how other
gRPC-dependent tests are excluded from PyPy in this repo.

Assisted-by: Claude Sonnet 4.6

* opentelemetry-test-utils: enable weaver tests on PyPy (#5176)

Weaver switched from gRPC C core to tonic (pure Rust) for its OTLP
server, so the epoll_wait EBADF crash that caused test flakiness on
PyPy no longer occurs. Verified by running the full weaver test suite
on PyPy 3.10 with grpcio compiled from source.

Remove the `platform_python_implementation != 'PyPy'` exclusions from
test-requirements.txt and the PyPy skip decorators added as a
workaround, so the weaver integration tests now run on PyPy as well.

Assisted-by: Claude Sonnet 4.6

* opentelemetry-test-utils: scope PyPy weaver tests to Linux only

grpcio has no PyPy wheel and the gRPC C core fails to build from source
with MSVC on Windows PyPy, so the previous "remove all PyPy exclusions"
change broke the Windows PyPy job. Gate the grpc deps off on PyPy+Windows
only; the weaver tests skip there via the existing _HAS_GRPC guard while
still running on Linux PyPy.

Assisted-by: Claude Opus 4.8 (1M context)

* opentelemetry-sdk: expose SynchronousMultiLogRecordProcessor and ConcurrentMultiLogRecordProcessor publicly

Fixes #5312

Assisted-by: Claude Sonnet 4.6

* address review feedback: remove redundant public API tests and unrelated changes

- Drop TestPublicApi test class; griffe already verifies the public API in CI
- Revert test-requirements.txt and tox.ini changes (unrelated to this PR)

Assisted-by: Claude Sonnet 4.6

* add changelog fragment for PR 5327

Assisted-by: Claude Sonnet 4.6

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Co-authored-by: Lukas Hering <40302054+herin049@users.noreply.github.com>