fix(redis): unboundlocalerror in redis utils

[emmettbutler]

This change resolves a programming error in redis_utils.py.

Fixes #9548

Checklist

• Change(s) are motivated and described in the PR description
• Testing strategy is described if automated tests are not included in the PR
• Risks are described (performance impact, potential for breakage, maintainability)
• Change is maintainable (easy to change, telemetry, documentation)
• Library release note guidelines are followed or label changelog/no-changelog is set
• Documentation is included (in-code, generated user docs, public corp docs)
• Backport labels are set (if applicable)
• If this PR changes the public interface, I've notified @DataDog/apm-tees.

Reviewer Checklist

• Title is accurate
• All changes are related to the pull request's stated goal
• Description motivates each change
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Change is maintainable (easy to change, telemetry, documentation)
• Release note makes sense to a user of the library
• Author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: emmett.butler/unbound-redis
Commit report: 1779ab8
Test service: dd-trace-py

✅ 0 Failed, 876 Passed, 12 Skipped, 7m 37.54s Total Time

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-06-14 17:14:54

Comparing candidate commit 1779ab8 in PR branch emmett.butler/unbound-redis with baseline commit bd047bc in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 221 metrics, 9 unstable metrics.

[sileht]

It's a dup of #9511