fix: add clang to dockerfile

[wangrunji0408]

I hereby agree to the terms of the RisingWave Labs, Inc. Contributor License Agreement.

What's changed and what's your intention?

#14761 introduced a clang dependency at build time. It was missing in the main dockerfile.

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
• I have added test labels as necessary. See details.
• I have added fuzzing tests or opened an issue to track them. (Optional, recommended for new SQL features Sqlsmith: Sql feature generation #7934).
• My PR contains breaking changes. (If it deprecates some features, please create a tracking issue to remove them in the future).
• All checks passed in ./risedev check (or alias, ./risedev c)
• My PR changes performance-critical code. (Please run macro/micro-benchmarks and show the results.)

• My PR contains critical fixes that are necessary to be merged into the latest release. (Please check out the details)

Documentation

• My PR needs documentation updates. (Please use the Release note section below to summarize the impact on users)

[BugenZhao]

The docker build succeeded, but the release job started to fail. 😕

https://buildkite.com/risingwavelabs/docker/builds/15062#_

[huangjw806]

The docker build succeeded, but the release job started to fail. 😕

https://buildkite.com/risingwavelabs/docker/builds/15062#_

I will fix it.