arrow

GH-35571: [C++][CI][Parquet] Change `EQ` to `FLOAT_EQ` in Decryption tests (#35605)



### Rationale for this change

CI would failed in Decrypt test in Windows MinGW. This is because in some MinGW version, it may generate
truncated stream test data in `GenerateSampleData<FloatType>`, as a fixing, here using `EXPECT_FLOAT_EQ`
to handle that problem

### What changes are included in this PR?

Change comparing float with `_EQ` to `FLOAT_EQ` and `DOUBLE_EQ` in unittest.

### Are these changes tested?

No

### Are there any user-facing changes?

No

* Closes: #35571

Lead-authored-by: mwish <maplewish117@gmail.com>
Co-authored-by: Antoine Pitrou <pitrou@free.fr>
Signed-off-by: Antoine Pitrou <antoine@python.org>