processing: fix grass' r.quantile parameter (fixes #21751)

(cherry picked from commit f1dbcc3)

Author: jef-n

python/plugins/processing/algs/grass7/description/r.quantile.txt

@@ -6,4 +6,4 @@ QgsProcessingParameterNumber|quantiles|Number of quantiles|QgsProcessingParamete
 QgsProcessingParameterString|percentiles|List of percentiles|None|False|True
 QgsProcessingParameterNumber|bins|Number of bins to use|QgsProcessingParameterNumber.Integer|1000000|True|1|None
 *QgsProcessingParameterBoolean|-r|Generate recode rules based on quantile-defined intervals|False
-QgsProcessingParameterFileDestination|html|Quantiles|Html files (*.html)|report.html|False
+QgsProcessingParameterFileDestination|file|Quantiles|Html files (*.html)|report.html|False