minor #12332 Reorganize UPGRADE-1.9 file to extract steps for Symfony v5.2 (GSadee)
minor #12332 Reorganize UPGRADE-1.9 file to extract steps for Symfony v5.2 (GSadee)

This PR was merged into the 1.9 branch.

Discussion
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| Q               | A
| --------------- | -----
| Branch?         | 1.9
| Bug fix?        | no
| New feature?    | no
| BC breaks?      | no
| Deprecations?   | no
| Related tickets | 
| License         | MIT


Commits
-------

16b9d64e230439a7b2bc9eeaf73fa20ee260c1dc Reorganize UPGRADE-1.9 file to extract steps for Symfony v5.2

loic425/Sylius,lchrusciel/Sylius,Zales0123/Sylius,pamil/Sylius,101medialab/Sylius,diimpp/Sylius,GSadee/Sylius,antonioperic/Sylius,antonioperic/Sylius,Zales0123/Sylius,pamil/Sylius,diimpp/Sylius,lchrusciel/Sylius,SyliusBot/Sylius,lchrusciel/Sylius,loic425/Sylius,Arminek/Sylius,GSadee/Sylius,Arminek/Sylius,diimpp/Sylius,Sylius/Sylius,SyliusBot/Sylius,pamil/Sylius,101medialab/Sylius,SyliusBot/Sylius,Arminek/Sylius,101medialab/Sylius,Sylius/Sylius,GSadee/Sylius,Sylius/Sylius,Zales0123/Sylius,antonioperic/Sylius,loic425/Sylius