PERF: column_arrays
Shaves a couple percent off of time_to_json_wide asv

Reprises #42824.
hmm just a couple of percent? > hmm just a couple of percent?

I'm seeing 13.5% locally

```
from asv_bench.benchmarks.io.json import *

self = ToJSONWide()
self.setup("columns", "df_td_int_ts")

%timeit self.time_to_json_wide("columns", "df_td_int_ts")
82.4 ms ± 1.71 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)  # <- master
71.3 ms ± 1.68 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)  # <- PR
``` just converned this is too specialy casey for json. but not a big deal. Column_arrays is already only for json

On Tue, Aug 31, 2021 at 4:55 PM Jeff Reback ***@***.***>
wrote:

> just converned this is too specialy casey for json. but not a big deal.
>
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 gentle ping; this is the last of the asv-identified perf PRs