chore: enable parallel frontend for rustc

[BugenZhao]

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

What's changed and what's your intention?

Enables the experimental parallel frontend feature for rustc under dev profile. For references, see https://blog.rust-lang.org/2023/11/09/parallel-rustc.html.

This reduces the time of incremental check from 30s to 18s with Apple M4 Pro. The major improvement is that the bottleneck of risingwave_meta spends significantly less time with parallel frontend.

Prev:

After:

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests

Documentation

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

Release note

If this PR includes changes that directly affect users or other significant modifications relevant to the community, kindly draft a release note to provide a concise summary of these changes. Please prioritize highlighting the impact these changes will have on users.

[xxchan]

can you also check full compilation with risingwave crates?

delete and rebuild

find target -name '*risingwave*' -type d -exec rm -rf {} + -o -name '*risingwave*' -delete

[BugenZhao]

can you also check full compilation with risingwave crates?

Sure. From 64.6s to 39.7s