test: add integration tests and CI job

[killme2008]

As the title said

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[Copilot]

Pull request overview

This PR adds comprehensive integration tests for the GreptimeDB Java Ingester and a corresponding GitHub Actions CI job to run these tests. The integration tests cover regular write, streaming write, and bulk write APIs, with verification through JDBC queries.

Changes:

• Added a new Maven module ingester-integration-tests with comprehensive test coverage for all write APIs
• Created integration test helper utilities to manage test lifecycle and verification
• Added a GitHub Actions CI job that spins up a GreptimeDB Docker container and runs the integration tests

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
pom.xml	Added the new ingester-integration-tests module to the parent POM
ingester-integration-tests/pom.xml	Maven configuration for the integration test module with necessary dependencies and failsafe plugin setup
ingester-integration-tests/src/test/resources/log4j2.xml	Log4j2 configuration for test logging
ingester-integration-tests/src/test/java/io/greptime/ITHelper.java	Helper utility class providing common test infrastructure
ingester-integration-tests/src/test/java/io/greptime/RegularWriteIT.java	Integration tests for regular write API
ingester-integration-tests/src/test/java/io/greptime/StreamingWriteIT.java	Integration tests for streaming write API
ingester-integration-tests/src/test/java/io/greptime/BulkWriteIT.java	Integration tests for bulk write API
.github/workflows/build.yml	Added CI job to run integration tests with a dockerized GreptimeDB instance

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[fengjiachun]

LGTM