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GH-41726: [C++][Parquet] Minor: moving EncodedStats by default rather than copying (#41727)



### Rationale for this change

Moving EncodedStats because it holds two std::string. This could benifit for non-SSO optimized data for FLBA/String statistics ( It seems to be useless for SSO optimized data?)

### What changes are included in this PR?

1. construct `EncodedStats` by `std::move`
2. Making uncompressing size checking ahead of compressing

### Are these changes tested?

Covered by existing.

### Are there any user-facing changes?

No

* GitHub Issue: #41726

Authored-by: mwish <maplewish117@gmail.com>
Signed-off-by: mwish <maplewish117@gmail.com>