[FEATURE] Remove Singleparts to Multiparts algorithm

This algorithm is no longer required - it's been replaced by
the 'Promote to multipart' and 'Collect geometries" algorithms.

Tagged as feature to remember to include in release notes

python/plugins/processing/algs/help/qgis.yaml

@@ -544,9 +544,6 @@ qgis:simplifygeometries: >
 
   The algorithm gives a choice of simplification methods, including distance based (the "Douglas-Peucker" algorithm), area based ("Visvalingam" algorithm) and snapping geometries to grid.
 
-qgis:singlepartstomultipart:
-
-
 qgis:singlesidedbuffer: >
   This algorithm buffers lines by a specified distance on one side of the line only.
 

python/plugins/processing/algs/qgis/QGISAlgorithmProvider.py

@@ -144,7 +144,6 @@
 from .ShortestPathPointToLayer import ShortestPathPointToLayer
 from .ShortestPathPointToPoint import ShortestPathPointToPoint
 from .SimplifyGeometries import SimplifyGeometries
-from .SinglePartsToMultiparts import SinglePartsToMultiparts
 from .SingleSidedBuffer import SingleSidedBuffer
 from .Slope import Slope
 from .Smooth import Smooth
@@ -292,7 +291,6 @@ def getAlgs(self):
                 ShortestPathPointToLayer(),
                 ShortestPathPointToPoint(),
                 SimplifyGeometries(),
-                SinglePartsToMultiparts(),
                 SingleSidedBuffer(),
                 Slope(),
                 Smooth(),

python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml

@@ -2683,7 +2683,7 @@ tests:
         name: expected/mean_coordinates.gml
         type: vector
 
-  - algorithm: qgis:singlepartstomultipart
+  - algorithm: native:collect
     name: single part to multipart
     params:
       FIELD: id