fix(common/redis): Pipeliner.Do queues every command twice when writeTimeout is set

[paulstadler-mesh]

Description

Fixes #4464.

Pipeliner.Do (both v8client.go and v9client.go) is missing a return in its writeTimeout > 0 branch: after queueing the command with a timeout context, execution falls through and queues the same command again with the unbounded context. Every command sent through a TxPipeline then executes twice per Exec whenever the component sets writeTimeout metadata.

Impact

• State transactions execute every operation twice. StateStore.Multi pipelines the CAS EVAL per operation, so a single transactional write runs the script twice — the version hash field increments by 2 per write, breaking ETag/first-write semantics.
• Dapr Workflow / actor state stores fail hard on daprd ≥ 1.17.9 (whose workflow engine plants the Lua first-write flag): every second workflow write fails with ERR user_script:14: failed to set key …||workflow||…||metadata. On earlier daprd the duplication is silent — versions inflate and transactional Redis CPU is ~doubled.
• Encountered in production against Azure Managed Redis: all Dapr Workflow submissions failed once daprd moved to 1.17.9; Redis CPU dropped materially once the duplication was removed. Reproduces identically through built-in state.redis and pluggable components (shared client).

Minimal repro and full analysis in #4464 (e.g. one transactional upsert on a fresh key → GET returns ETag 2).

Fix

Add the missing return (mirrors the existing pattern in DoWrite/DoRead on the same clients).

Testing

New regression test TestPipelinerDoQueuesOnceWithWriteTimeout drives a pipelined INCR through both v8 and v9 clients against miniredis and asserts single execution, with and without writeTimeout (fails on the previous code with counter=2).

Checklist

• Code compiles correctly
• Created/updated tests
• Extended the documentation — n/a (no user-facing behavior beyond the bug fix)

[paulstadler-mesh]

@mikeee sorry for the direct ping — this one's a 2-line fix (+regression test) for #4464: Pipeliner.Do double-queues every pipelined command when writeTimeout is set, which breaks transactional ETag/first-write semantics (and fails Dapr Workflow state saves on daprd ≥ 1.17.9). We've been running the fix in production for a couple of weeks.

The CI workflows are sitting at awaiting approval (fork PR) — if you could approve the runs, everything else should go green from there. Happy to make any changes needed. Thanks!