ci: Exclude turborepo-lsp and turborepo-schema-gen from test builds (#12075)
## Summary
- Excludes `turborepo-lsp` and `turborepo-schema-gen` from all `cargo
nextest` and `cargo llvm-cov nextest` runs in CI.
## Why
Both crates are leaf nodes with zero reverse dependencies — nothing in
the workspace depends on them. They have no tests we care about
exercising in the main test workflow, but they were being compiled on
every run because the workspace `members` glob catches them.
`turborepo-lsp` is particularly expensive because it depends on
`turborepo-lib`, which pulls in ~30 transitive workspace crates. It
compiles dead last in the dependency graph and contributes nothing to
test coverage.
Lint and `cargo check` still cover both crates.
## Testing
The change is purely additive `--exclude` flags on existing CI commands.
Existing tests are unaffected since these crates had no meaningful test
coverage being exercised.