Pass unique context and cancel func to worker during compaction

[anna-tran]

• I added CHANGELOG entry for this change.
• Change is not relevant to the end user.

Changes

This PR creates a new context for each compaction worker and also passes the cancel function for that worker's context. It introduces a new monitoring function in the lifecycle callback that allows implementations of the lifecycle to cancel the context if there is any issue with the compaction plan/process while the compaction is underway.

This allows a single compaction to be aborted/failed in case of an issue in the planning phase, and only affect that single compaction job.

The change will help to address this issue in Cortex: cortexproject/cortex#7135

Verification

make build runs successfully.

[GiedriusS]

Why cannot whoever calls Plan() cancel the context when they need to cancel it?

[anna-tran]

Why cannot whoever calls Plan() cancel the context when they need to cancel it?

This is also an option. We could make a new error chan for each worker (or reuse the existing one) in the compact method and spin up a new goroutine which waits to see if any error is received. If received then it can cancel the context, allowing the compaction to abort. What do you think?

[GiedriusS]

Could you show changes on the Cortex side? I don't get why we need to pass the cancel function.

[anna-tran]

I added a comment regarding how this would work in Cortex, and will update that with proposed code changes.
cortexproject/cortex#7135 (comment)