[otlp-transformer] update protos submodule to latest version

[pichlermarc]

Description

The protos submodule in the @opentelemetry/otlp-transformer package is outdated. Goal of this issue is to update the submodule to point to the latest release of the opentelemetry-proto repository. To do so you can follow the documentation in submodule.md.

This issue is considered done when:

• the protos submodule in the @opentelemetry/otlp-transformer package is updated to the latest release of opentelemetry-proto repository
  • see submodule.md for instructions
• changes have been tested locally by running npm run compile && npm run test && npm run test:browser from the top level of the repository
• If improv(tests): add e2e test with collector for all of our OTLP exporters #2157 (or any follow-up issue derived from it) is NOT done yet: changes have been tested manually by using the exporter example, cycle through all exporters (grpc, json, protobuf) by commenting and uncommenting these lines (metrics, traces)
  • this needs npm run compile to be run first otherwise that static code will NOT be re-generated with the new version
• any changes to the update process have been documented in submodule.md, if any