createTableBucket ran `weed shell` via exec.Command with no deadline.
When the shell's first command retries on a transient master connection
blip, the trailing `exit` on stdin never gets processed and the
subprocess blocks until the outer 20m `go test` timeout fires — the
surfacing symptom is a flaky 20m panic with no diagnostic output.
Wrap the invocation in exec.CommandContext with a 30s timeout, matching
the existing pattern in test/s3tables/catalog_risingwave/setup_test.go.