fix: opentelemetry-bom to be in third-party-dependencies BOM

[suztomo]

Importing opentelemetry-bom in gapic-generator-java-bom (and thus Google Cloud Libraries BOM) wrongly implies that we (Google) publish the OpenTelemetry artifacts.

https://jlbp.dev/JLBP-15 states:

Your project's BOM should not include any of your dependencies on other libraries.

In this change, the opentelemetry-bom is declared in the third-party-dependencies BOM and thus will be excluded in the Google Cloud Libraries BOM, which does not import the third-party-dependencies BOM.

Related to b/338624813

[sonarqubecloud[bot]]

Quality Gate passed for 'gapic-generator-java-root'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[sonarqubecloud[bot]]

Quality Gate passed for 'java_showcase_integration_tests'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud