Delete unused cargo.lock files

Summary:
Similarly to yarn workspaces, for cargo crates that are members of a workspace, there's a single Cargo.lock in repo root.
The package-specific lockfiles can now be removed.

Removed 15 lockfiles, leaving only 5: one for workspace lock, remaining four for non-workspace crates

Depends on D12140

Test Plan:
cargo build for all packages in workspace

cargo build --workspace

Reviewers: varun, kamil

Reviewed By: kamil

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D12168