[Java]: Refactor test for better use of matrix

[edburns]

Predecessor: #1917

Problem

The java-sdk-tests.yml workflow has two separate jobs — java-sdk and java-sdk-inprocess — that duplicate ~20 lines of identical setup (checkout, setup-java, setup-node). This duplication makes maintenance harder: action version pin bumps must be applied in two places.

Proposal

Add a transport: [default, inprocess] dimension to the existing test-jdk matrix in the java-sdk job, and remove the standalone java-sdk-inprocess job.

Matrix shape

strategy:
  fail-fast: false
  matrix:
    test-jdk: ["25", "17"]
    transport: ["default", "inprocess"]
    exclude:
      - test-jdk: "17"
        transport: "inprocess"

The exclude prevents the JDK-17 + inprocess combination, which is not meaningful (the native library targets a single JDK).

Conditional step adjustments

• Steps already guarded with if: matrix.test-jdk == '25' gain an additional && matrix.transport == 'default' where they should not run for the inprocess leg (e.g., spotless, javadoc, doc-version test).
• The mvn invocation switches based on matrix.transport: mvn clean verify -Pinprocess for inprocess, the existing split build-then-test flow for default.
• Artifact names and test report titles include the transport value for clarity.

Benefits

• Less duplication — shared setup steps defined once.
• Easier maintenance — action pin bumps in one place.
• Consistent naming — job names like Java SDK Tests (JDK 25, inprocess) clearly identify the configuration.

Risks

• Slightly more complex if: conditionals, but manageable given the existing pattern.