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GH-41004: [C++][FS][Azure] Don't run TestGetFileInfoGenerator() with Valgrind (#41163)

### Rationale for this change

`GetFileInfo()` with generator reports false positive memory leak in Azure SDK for C++.

### What changes are included in this PR?

Don't run `TestGetFileInfoGenerator()` with Valgrind.

### Are these changes tested?

Yes.

### Are there any user-facing changes?

No.
* GitHub Issue: #41004

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