[CHORE] move spanner-migrations to rust/ top level

[rescrv]

Description of changes

Relocate the spanner-migrations crate from rust/rust-sysdb/spanner-migrations/
to rust/spanner-migrations/ to align with the flat structure of other crates
in the rust workspace. Update workspace members in Cargo.toml accordingly.

Test plan

Tilt up locally + CI

Migration plan

N/A

Observability plan

N/A

Documentation Changes

N/A

Co-authored-by: AI

[github-actions]

Reviewer Checklist

Please leverage this checklist to ensure your code review is thorough before approving

Testing, Bugs, Errors, Logs, Documentation

• Can you think of any use case in which the code does not behave as intended? Have they been tested?
• Can you think of any inputs or external events that could break the code? Is user input validated and safe? Have they been tested?
• If appropriate, are there adequate property based tests?
• If appropriate, are there adequate unit tests?
• Should any logging, debugging, tracing information be added or removed?
• Are error messages user-friendly?
• Have all documentation changes needed been made?
• Have all non-obvious changes been commented?

System Compatibility

• Are there any potential impacts on other parts of the system or backward compatibility?
• Does this change intersect with any items on our roadmap, and if so, is there a plan for fitting them together?

Quality

• Is this code of a unexpectedly high quality (Readability, Modularity, Intuitiveness)

[propel-code-bot]

Relocate spanner-migrations crate in workspace

This PR relocates the spanner-migrations crate from rust/rust-sysdb/spanner-migrations to rust/spanner-migrations, aligning it with the flattened Rust workspace layout. The primary visible change updates the workspace members list in the root Cargo.toml to reflect the new crate path.

Key Changes

• Updated the root Cargo.toml workspace members array to register rust/spanner-migrations instead of the nested rust/rust-sysdb/spanner-migrations path
• Renamed/moved the spanner-migrations crate directory to rust/ root (by implication from the rename-focused change set)

Affected Areas

• Cargo.toml workspace configuration
• rust/spanner-migrations crate location

This summary was automatically generated by @propel-code-bot