Auto merge of #131988 - matthiaskrgr:rollup-tx173wn, r=matthiaskrgr

Rollup of 4 pull requests

Successful merges:

 - #126588 (Added more scenarios where comma to be removed in the function arg)
 - #131728 (bootstrap: extract builder cargo to its own module)
 - #131968 (Rip out old effects var handling code from traits)
 - #131981 (Remove the `BoundConstness::NotConst` variant)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors