Create ecosystem process for stewardship of GraphQL deprecation removals

This issue is part of the Epic &7155 (closed). Please see that Epic for more context.

About

This issue is currently a meta issue to gather ideas on how devopsecosystem can oversee the removal of deprecated schema from the GraphQL API. Ideally, the process should be light and reliable.

Some ideas that came out of #334278 (comment 735087926) to support &7155 (closed):

• Ecosystem should create an Epic to track upcoming GraphQL deprecation removals for the next major milestone, repeating for each major milestone, this could be automated #334278 (comment 735575125) or just a reminder could be added to our milestone planning issue #334278 (comment 735104142).
• 2 milestones before the upcoming major release, check that all deprecated schema has been correctly announced #345972 (closed), and ping people if not.
• On major releases ensure that all removals are announced.

Proposal

The proposal is to make this process self-serve as much as possible #345974 (comment 849203497).