Remove workaround disabling Parquet page index reading for encrypted files

[adamreeve]

datafusion/datafusion/datasource-parquet/src/opener.rs

Lines 158 to 162 in d19bf52

	// For now, page index does not work with encrypted files. See:
	// https://github.com/apache/arrow-rs/issues/7629
	if file_decryption_properties.is_some() {
	enable_page_index = false;
	}

This was fixed in apache/arrow-rs#7633, released in parquet 55.2.0, so this workaround can be removed now.