cargo: compile all packages with -C debuginfo=line-tables-only

This causes `rustc` to only emit enough debuginfo to emit backtraces with
filepaths and line numbers, but nothing more. This has a massive impact on the
size of `target/` in practice; a clean rebuild of all dependencies (tested via
`cargo nextest run --workspace --no-run`) goes from ~5.5GiB to 2.1GiB.

This should help us stave off the dreaded sacrificial "delete `target/` to save
disk space" ritual that we occasionally must invoke (today I realized my `jj`
build dir was over 120GiB.)

Signed-off-by: Austin Seipp <[email protected]>
Change-Id: Ia1f31b87da89e59d77f54a3d79cb45113db215dc

Cargo.toml

@@ -122,8 +122,13 @@ testutils = { path = "lib/testutils" }
 
 [profile.dev.package."*"]
 codegen-units = 1
+debug = "line-tables-only"
 opt-level = 3
 
+[profile.dev]
+debug = "line-tables-only"
+
 [profile.release]
+debug = "line-tables-only"
 strip = "debuginfo"
 codegen-units = 1