deps(common-protos): use JUnit 5 artifact ID as per ${junit.verison}

[diegomarquezp]

Fixes observed failures in last nightly graalvm runs

• GraalVM B
• GraalVM C

The failure is as follows:

07:21:37:407 [ERROR] Failed to execute goal on project proto-google-common-protos: Could not resolve dependencies for project com.google.api.grpc:proto-google-common-protos:jar:2.71.0-SNAPSHOT: The following artifacts could not be resolved: junit:junit:jar:5.11.4 (absent): Could not find artifact junit:junit:jar:5.11.4 in maven-central (https://repo1.maven.org/maven2) -> [Help 1]

Due to junit:junit being 4.x api. For 5.x we use the junit:junit-bom

[gemini-code-assist]

Code Review

This pull request updates the JUnit dependency in java-common-protos/pom.xml from junit:junit to org.junit:junit-bom. A critical issue was identified regarding the declaration of the junit-bom artifact: as a Bill of Materials (BOM), it requires the addition of pom and import to prevent Maven from attempting to resolve it as a JAR file, which would lead to a build failure.

[diegomarquezp]

• Investigate why only on GraalVM.
• Try local reproduction
• Find out whether there common-protos is a special case in the builds