Drop get_absolute_url methods

[IKarbowiak]

Resolves #5022

Pull Request Checklist

1. Privileged views and APIs are guarded by proper permission checks.
2. All visible strings are translated with proper context.
3. All data-formatting is locale-aware (dates, numbers, and so on).
4. Database queries are optimized and the number of queries is constant.
5. Database migration files are up to date.
6. The changes are tested.
7. GraphQL schema and type definitions are up to date.
8. Changes are mentioned in the changelog.

[django-queries]

Here is the report for aabb48e (mirumee/saleor @ drop-get-absolute-url-methods)
Base comparison is ba45ef0.

No differences were found. (click me)

# api.benchmark category
  test name                                  	left count 	right count	duplicate count
  -------------------------------------------	-----------	-----------	---------------
  category view                              	         23	         23	              0

# api.benchmark checkout
  test name                                  	left count 	right count	duplicate count
  -------------------------------------------	-----------	-----------	---------------
  add billing address to checkout            	         34	         34	             20
  add shipping to checkout                   	          7	          7	              0
  checkout payment charge                    	         10	         10	              0
  complete checkout                          	          8	          8	              0
  create checkout                            	          5	          5	              1

# api.benchmark collection
  test name                                  	left count 	right count	duplicate count
  -------------------------------------------	-----------	-----------	---------------
  collection view                            	         21	         21	              0

# api.benchmark homepage
  test name                                  	left count 	right count	duplicate count
  -------------------------------------------	-----------	-----------	---------------
  featured products list                     	         20	         20	              0
  retrieve main menu                         	          8	          8	              0
  retrieve product list                      	          6	          6	              0
  retrieve secondary menu                    	          8	          8	              0
  retrieve shop                              	          2	          2	              0
  user checkout details                      	         53	         53	             28

# api.benchmark product
  test name                                  	left count 	right count	duplicate count
  -------------------------------------------	-----------	-----------	---------------
  product details                            	         17	         17	              3
  retrieve product attributes                	          9	          9	              0

# api.benchmark variant
  test name                                  	left count 	right count	duplicate count
  -------------------------------------------	-----------	-----------	---------------
  product variant bulk create                	         51	         51	              3
  retrieve variant list                      	         23	         23	              9

# api product sorting attributes
  test name                                  	left count 	right count	duplicate count
  -------------------------------------------	-----------	-----------	---------------
  sort product not having attribute data     	         21	         21	              0

[codecov]

Codecov Report

Merging #5299 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #5299   +/-   ##
=======================================
  Coverage   91.59%   91.59%           
=======================================
  Files         283      283           
  Lines       18154    18154           
  Branches     1580     1580           
=======================================
  Hits        16628    16628           
  Misses       1103     1103           
  Partials      423      423

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