Prepare for migration to new runtime metrics

[dashpole]

Part of #5655

This is a refactoring to prepare for the implementation of the new runtime metrics. It:

• Adds support for OTEL_GO_X_DEPRECATED_RUNTIME_METRICS, which can be set to true or false to enable/disable the existing runtime metrics. It initially defaults to true while the new metrics are under development.
• Moves the existing runtime metrics implementation to its own internal package, deprecatedruntime, to clearly separate it from the new metrics being added, and to make the eventual removal easier.

This does not change any of the metrics generated, or the public API surface of the runtime metrics package.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 7.34463% with 164 lines in your changes missing coverage. Please review.

Project coverage is 63.9%. Comparing base (a794a70) to head (8c344a3).

Additional details and impacted files

[](https://app.codecov.io/gh/open-telemetry/opentelemetry-go-contrib/pull/5747?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-telemetry) ```diff @@ Coverage Diff @@ ## main #5747 +/- ## ===================================== Coverage 63.9% 63.9% ===================================== Files 195 197 +2 Lines 12267 12285 +18 ===================================== + Hits 7849 7862 +13 - Misses 4196 4201 +5 Partials 222 222 ``` | [Files](https://app.codecov.io/gh/open-telemetry/opentelemetry-go-contrib/pull/5747?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-telemetry) | Coverage Δ | | |---|---|---| | [instrumentation/runtime/internal/x/x.go](https://app.codecov.io/gh/open-telemetry/opentelemetry-go-contrib/pull/5747?src=pr&el=tree&filepath=instrumentation%2Fruntime%2Finternal%2Fx%2Fx.go&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-telemetry#diff-aW5zdHJ1bWVudGF0aW9uL3J1bnRpbWUvaW50ZXJuYWwveC94Lmdv) | `100.0% <100.0%> (ø)` | | | [instrumentation/runtime/runtime.go](https://app.codecov.io/gh/open-telemetry/opentelemetry-go-contrib/pull/5747?src=pr&el=tree&filepath=instrumentation%2Fruntime%2Fruntime.go&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-telemetry#diff-aW5zdHJ1bWVudGF0aW9uL3J1bnRpbWUvcnVudGltZS5nbw==) | `0.0% <0.0%> (ø)` | | | [...tion/runtime/internal/deprecatedruntime/runtime.go](https://app.codecov.io/gh/open-telemetry/opentelemetry-go-contrib/pull/5747?src=pr&el=tree&filepath=instrumentation%2Fruntime%2Finternal%2Fdeprecatedruntime%2Fruntime.go&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-telemetry#diff-aW5zdHJ1bWVudGF0aW9uL3J1bnRpbWUvaW50ZXJuYWwvZGVwcmVjYXRlZHJ1bnRpbWUvcnVudGltZS5nbw==) | `0.0% <0.0%> (ø)` | |

[dashpole]

I was going to keep the same scope for the deprecated metrics. It doesn't make sense to me to modify the scope if they are going away anyways.

[MrAlias]

Looks like this introduced a broken link. I'll look into submitting a fix.