cli: push new non-tracking bookmarks by default, rename --allow-new flag #17265

Job	Run time
Build jj-lib without Git support	1m 7s
build (ubuntu-latest)	5m 6s
build (macos-13)	6m 10s
cargo-deny (advisories)	22s
build (macos-14)	4m 3s
cargo-deny (bans licenses sources)	22s
build (windows-latest)	10m 55s
build (ubuntu-latest, --all-features)	5m 55s
Check protos	31s
Check that MkDocs can build the docs	13s
Check that MkDocs can build the docs with latest Python and uv	11s
Check formatting	22s
Clippy check	2m 35s
	37m 52s

Provide feedback