Enable all benchmarks in CI

[XSAM]

Part of #4537

Here is the recent benchmark result from the CI:

• https://github.com/open-telemetry/opentelemetry-go/actions/runs/10067601185
• https://github.com/open-telemetry/opentelemetry-go/actions/runs/10068023613
• https://github.com/open-telemetry/opentelemetry-go/actions/runs/10072452529

Though the results are pretty stable, they only run for very limited benchmarks, which cannot reflect the stability when running more benchmarks.

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This PR enables all benchmarks in CI so we can obtain accurate stability results. I also removed the timeout flag for the benchmark test, as some benchmarks contain a lot of sub-benchmarks, which will timeout anyway if we have a 60-second timeout. (Go does not offer timeout for single benchmark or test)