chore: migrate java tests

[JoeWang1127]

In this PR:

• Migrate test_language_java.py and test resources from synthtool.
• Remove synthtool installation step in CI.
• Remove unused methods in java.py.
• Refactor code to align with the current coding style.

[JoeWang1127]

We don't want to render ${{ secrets.CLOUD_JAVA_BOT_TOKEN }}, use raw to ignore the variable.

[snippet-bot]

Here is the summary of possible violations 😱

There are 3 possible violations for not having product prefix.

• library_generation/test/resources/test-owlbot/testdata/synth-with-flag.py:38, tag fix-dead-link
• library_generation/test/resources/test-owlbot/testdata/synth-with-syntax-error-py:38, tag fix-dead-link
• library_generation/test/resources/test-owlbot/testdata/synth.py:36, tag fix-dead-link

There are format violations for 3 region tags.

• library_generation/test/resources/test-owlbot/testdata/synth-with-flag.py:38, tag fix-dead-link
• library_generation/test/resources/test-owlbot/testdata/synth-with-syntax-error-py:38, tag fix-dead-link
• library_generation/test/resources/test-owlbot/testdata/synth.py:36, tag fix-dead-link

The end of the violation section. All the stuff below is FYI purposes only.

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Here is the summary of changes.

You are about to add 3 region tags.

• library_generation/test/resources/test-owlbot/testdata/synth-with-flag.py:38, tag fix-dead-link
• library_generation/test/resources/test-owlbot/testdata/synth-with-syntax-error-py:38, tag fix-dead-link
• library_generation/test/resources/test-owlbot/testdata/synth.py:36, tag fix-dead-link

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[blakeli0]

Is this file still used in unit tests? Same question for all other test files like sponge-log-golden.xml. I don't see them being used so they should've probably be removed from synthtool long time ago. Can we only keep the ones used in unit tests?

[JoeWang1127]

Thanks for the suggestion.

I removed unused test resources.

[sonarcloud]

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

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[sonarcloud]

Quality Gate passed for 'java_showcase_integration_tests'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud