build: try to optimize compile time

A while ago we used sccache to reduced a lot of compile time in CI, but didn’t really look into our codebase and dependencies to improve it. So the local DX is not improved.

We haven’t optimized it for long and it also bloated a lot, so it’s worth to at least take a look to see if there’s any low-hanging fruits.

Some simple observations:

• risingwave_common – risingwave_expr – risingwave_connector is the pipeline breaker
• aws-sdk-ec2 is the 2nd largest monster dependency (70+s!!????), but we only have very simple usage of it (github.com/risingwavelabs/risingwave/blob/main/src/meta/src/rpc/cloud_provider.rs). It’s not very economical and may be worth to build HTTP request manually with reqsign (or use aws-sigv4 since we already have that dependency by aws-sdk-s3)