chore: merge `f/split-subgraph` into `f/split`

Description

Merges aggregate changes from the subgraph split to the main split branch. Please see the CHANGELOG.md inside packages/subgraph for more info.

Task ID: OS-1154

[x] Breaking change (fix or feature that would cause existing functionality to not work as expected)

[x] I have selected the correct base branch.
[x] I have performed a self-review of my own code.
[x] I have commented my code, particularly in hard-to-understand areas.
[x] My changes generate no new warnings.
[x] Any dependent changes have been merged and published in downstream modules.
[x] I ran all tests with success and extended them if necessary.
[x] I have updated the CHANGELOG.md file in the root folder.
[x] I have updated the DEPLOYMENT_CHECKLIST file in the root folder.
[x] I have updated the UPDATE_CHECKLIST file in the root folder.
[x] I have updated the Subgraph and added a QA URL to the description of this PR.