ARROW-11708: [Rust] fix Rust 2021 linting warnings

[houqp]

Sample warning:

warning: panic message is not a string literal                                                                                                                                                                                 
    --> arrow/src/json/reader.rs:2049:13                                                                                                                                                                                       
     |                                                                                                                                                                                                                         
2049 |             format!("{:?} != {:?}", expected.data(), read.data())                                                                                                                                                       
     |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^                                                                                                                                                       
     |                                                                                                                                                                                                                         
     = note: `#[warn(non_fmt_panic)]` on by default                                                                                                                                                                            
     = note: this is no longer accepted in Rust 2021 

[github-actions]

https://issues.apache.org/jira/browse/ARROW-11708

[codecov-io]

Codecov Report

Merging #9535 (696b14d) into master (c100a5c) will decrease coverage by 0.00%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master    #9535      +/-   ##
==========================================
- Coverage   82.27%   82.26%   -0.01%     
==========================================
  Files         244      244              
  Lines       55371    55373       +2     
==========================================
+ Hits        45554    45555       +1     
- Misses       9817     9818       +1     

Impacted Files	Coverage Δ
rust/arrow/src/json/reader.rs	83.57% <0.00%> (-0.06%)	⬇️
rust/arrow/src/json/writer.rs	86.17% <0.00%> (ø)
rust/arrow/src/util/test_util.rs	90.90% <0.00%> (ø)
...ion-testing/src/bin/arrow-json-integration-test.rs	0.00% <0.00%> (ø)
rust/arrow/src/record_batch.rs	83.70% <75.00%> (-0.63%)	⬇️
rust/datafusion/src/physical_plan/planner.rs	79.58% <100.00%> (ø)
rust/parquet/src/encodings/encoding.rs	95.05% <0.00%> (+0.19%)	⬆️

---

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[alamb]

Looks great. Thanks @houqp

[alamb]

This is a good one. 👍

[alamb]

Given this is unlikely to be controversial, I am just merging it in as is

[codecov-commenter]

Codecov Report

❌ Patch coverage is 33.33333% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.26%. Comparing base (c100a5c) to head (696b14d).

Files with missing lines	Patch %	Lines
rust/arrow/src/json/reader.rs	0.00%	2 Missing ⚠️
rust/arrow/src/json/writer.rs	0.00%	2 Missing ⚠️
rust/arrow/src/util/test_util.rs	0.00%	2 Missing ⚠️
rust/arrow/src/record_batch.rs	75.00%	1 Missing ⚠️
...ion-testing/src/bin/arrow-json-integration-test.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9535      +/-   ##
==========================================
- Coverage   82.27%   82.26%   -0.01%     
==========================================
  Files         244      244              
  Lines       55371    55373       +2     
==========================================
+ Hits        45554    45555       +1     
- Misses       9817     9818       +1     

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