Introduce forced compilation deps for consistent CLI builds

[Swiddis]

Description

It looks like sometimes the CLI fails to build in CI because of a compilation race condition -- this adds some explicit dependencies to hopefully fix the flakiness.

Will rerun a few times to see if CLI failures continue.

Related Issues

Flaky CI coming up in #5129 and #5080

Check List

• New functionality includes testing.
• New functionality has been documented.
• New functionality has javadoc added.
• New functionality has a user manual doc added.
• New PPL command checklist all confirmed.
• API changes companion pull request created.
• Commits are signed per the DCO using --signoff or -s.
• Public documentation issue/PR created.

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[coderabbitai]

📝 Walkthrough

Summary by CodeRabbit

Release Notes

• Build Improvements
  • Enhanced build configuration across multiple modules to ensure proper task execution order and improve overall build stability.

Walkthrough

These changes add explicit task dependencies to compileJava tasks across four Gradle modules to synchronize the build process and prevent race conditions in parallel builds. Each module's compileJava task now waits for prerequisite module class generation before proceeding.

Changes

Cohort / File(s)	Summary
Build synchronization dependencies opensearch/build.gradle, ppl/build.gradle, protocol/build.gradle, sql/build.gradle	Added explicit dependencies to compileJava tasks to wait for classes tasks from dependent modules (core, common, opensearch, protocol), preventing race conditions in parallel builds.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: adding forced compilation dependencies to address CLI build issues, which directly matches the changeset across four build.gradle files.
Description check	✅ Passed	The description is clearly related to the changeset, explaining the motivation (fixing compilation race conditions) and linking to related issues, though it could include more technical detail about the specific files modified.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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No actionable comments were generated in the recent review. 🎉

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[Swiddis]

CLI build passed 3 times in a row, in another PR it was failing 2/3 times so I suspect this did the trick

[penghuo]

CLI build passed 3 times in a row, in another PR it was failing 2/3 times so I suspect this did the trick

Gradle should normally infer compileJava → :dep:classes ordering from implementation/api project dependencies automatically. Is there something specific about the CLI composite build setup that breaks this?