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GH-37237: [C++] Set extraction time to all downloaded contents timestamp (#37238)

### Rationale for this change

The "The DOWNLOAD_EXTRACT_TIMESTAMP option was not given and policy CMP0135 is not set." warnings are noisy.

### What changes are included in this PR?

Set `CMP0135` policy.

### Are these changes tested?

Yes.

### Are there any user-facing changes?

Yes.
* Closes: #37237

Authored-by: Sutou Kouhei <kou@clear-code.com>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>