bugfix: fix error when get_coerced_window_frame meet utf8

[jackwener]

Which issue does this PR close?

Closes #5233.
Part of #4685

Rationale for this change

What changes are included in this PR?

Are these changes tested?

No need, current tests can cover this problem, but it was hidden by skip_failed_rules.

set pub skip_failed_rules: bool, default = false

Before this PR, sort_on_window_null_string will fail.
After this PR, they will success.

Are there any user-facing changes?

[jackwener]

cc @HaoYang670 @liukun4515 @alamb

[mustafasrepo]

LGTM!. Thanks

[alamb]

In general I think it would be neat to have some sort of test coverage in the sense that if this code was removed, all the tests still pass. So the bug could get reintroduced and we would not catch the regression

For example, perhaps we could set https://docs.rs/datafusion/17.0.0/datafusion/config/struct.OptimizerOptions.html#structfield.skip_failed_rules to false for a test that was failing in this way 🤔

[ursabot]

Benchmark runs are scheduled for baseline = 0a5e8ae and contender = f2ce2b9. f2ce2b9 is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ec2-t3-xlarge-us-east-2] ec2-t3-xlarge-us-east-2
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on test-mac-arm] test-mac-arm
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ursa-i9-9960x] ursa-i9-9960x
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ursa-thinkcentre-m75q] ursa-thinkcentre-m75q
Buildkite builds:
Supported benchmarks:
ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python, R. Runs only benchmarks with cloud = True
test-mac-arm: Supported benchmark langs: C++, Python, R
ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript
ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java