fix(trace)!: remove span_path resource helper method from v2; modify retry configs; standardize usage of 'optional' and 'required' for args in docstrings; add 2.7 deprecation warning (via synth)

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Log from Synthtool

synthtool > Executing /tmpfs/src/git/autosynth/working_repo/trace/synth.py.
synthtool > Ensuring dependencies.
synthtool > Pulling artman image.
latest: Pulling from googleapis/artman
Digest: sha256:264654a37596a44b0668b8ce6ac41082d713f6ee150b3fc6425fa78cc64e4f20
Status: Image is up to date for googleapis/artman:latest
synthtool > Cloning googleapis.
synthtool > Running generator for google/devtools/cloudtrace/artman_cloudtrace_v1.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/python/trace-v1.
synthtool > Copy: /home/kbuilder/.cache/synthtool/googleapis/google/devtools/cloudtrace/v1/trace.proto to /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/python/trace-v1/google/cloud/trace_v1/proto/trace.proto
synthtool > Placed proto files into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/python/trace-v1/google/cloud/trace_v1/proto.
synthtool > Replaced 'from google.devtools.cloudtrace_v1.proto import ' in google/cloud/trace_v1/proto/trace_pb2_grpc.py.
synthtool > Running generator for google/devtools/cloudtrace/artman_cloudtrace_v2.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/python/trace-v2.
synthtool > Copy: /home/kbuilder/.cache/synthtool/googleapis/google/devtools/cloudtrace/v2/trace.proto to /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/python/trace-v2/google/cloud/trace_v2/proto/trace.proto
synthtool > Copy: /home/kbuilder/.cache/synthtool/googleapis/google/devtools/cloudtrace/v2/tracing.proto to /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/python/trace-v2/google/cloud/trace_v2/proto/tracing.proto
synthtool > Placed proto files into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/python/trace-v2/google/cloud/trace_v2/proto.
synthtool > Replaced 'from google.devtools.cloudtrace_v2.proto import ' in google/cloud/trace_v2/proto/tracing_pb2_grpc.py.
synthtool > Replaced 'from google.devtools.cloudtrace_v2.proto import ' in google/cloud/trace_v2/proto/tracing_pb2.py.
.coveragerc
.flake8
MANIFEST.in
docs/_static/custom.css
docs/_templates/layout.html
noxfile.py.j2
setup.cfg
Running session blacken
Creating virtual environment (virtualenv) using python3.6 in .nox/blacken
pip install black
black google tests docs
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v1/__init__.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v1/gapic/enums.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v1/gapic/trace_service_client_config.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/docs/conf.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v1/gapic/transports/trace_service_grpc_transport.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v1/types.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v2/__init__.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v1/proto/trace_pb2_grpc.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v2/gapic/enums.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v2/gapic/trace_service_client_config.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v2/gapic/transports/trace_service_grpc_transport.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v1/gapic/trace_service_client.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v2/proto/trace_pb2_grpc.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v2/gapic/trace_service_client.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v2/proto/tracing_pb2_grpc.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v2/proto/tracing_pb2.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v2/types.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/tests/unit/gapic/v2/test_trace_service_client_v2.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/tests/unit/gapic/v1/test_trace_service_client_v1.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v1/proto/trace_pb2.py
reformatted /tmpfs/src/git/autosynth/working_repo/trace/google/cloud/trace_v2/proto/trace_pb2.py
All done! ✨ 🍰 ✨
21 files reformatted, 24 files left unchanged.
Session blacken was successful.
synthtool > Wrote metadata to synth.metadata.