CLN: replace %s syntax with .format in pandas.util
Progress towards #16130

- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`

Replaced `%s` syntax with `.format` in pandas.util.  Additionally, made some of the existing positional `.format` code more explicit.  Left the `Substitution` class in _decorators.py as-is, since it appears to impact docstrings across the entire codebase.


# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17224?src=pr&el=h1) Report
> Merging [#17224](https://codecov.io/gh/pandas-dev/pandas/pull/17224?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/989babdec1f11edd208d94eaf5806f931ecb8fc9?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `62.5%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/17224/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/17224?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #17224      +/-   ##
==========================================
+ Coverage      91%   91.01%   +<.01%     
==========================================
  Files         162      162              
  Lines       49517    49518       +1     
==========================================
+ Hits        45063    45067       +4     
+ Misses       4454     4451       -3
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.79% <62.5%> (+0.02%)` | :arrow_up: |
| #single | `40.26% <0%> (-0.07%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/17224?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/17224?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `100% <ø> (ø)` | :arrow_up: |
| [pandas/util/\_print\_versions.py](https://codecov.io/gh/pandas-dev/pandas/pull/17224?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvX3ByaW50X3ZlcnNpb25zLnB5) | `15.71% <0%> (ø)` | :arrow_up: |
| [pandas/util/\_validators.py](https://codecov.io/gh/pandas-dev/pandas/pull/17224?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvX3ZhbGlkYXRvcnMucHk=) | `93.75% <100%> (ø)` | :arrow_up: |
| [pandas/util/\_decorators.py](https://codecov.io/gh/pandas-dev/pandas/pull/17224?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvX2RlY29yYXRvcnMucHk=) | `66% <80%> (+0.34%)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/17224?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/17224?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.71% <0%> (-0.1%)` | :arrow_down: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/17224?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `65.05% <0%> (+1.81%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17224?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17224?src=pr&el=footer). Last update [989babd...1ea5b0f](https://codecov.io/gh/pandas-dev/pandas/pull/17224?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
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