test: split loadtests by request type

[steve-chavez]

Problem

Currently it's not possible to know accurately if performance is dropping or increasing on a PR based on deltas of the "mixed" loadtest, this is because all the requests types are contained in a single loadtest:

postgrest/test/load/targets.http

Lines 1 to 41 in dee7d6f

	GET http://postgrest/
	Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.e30.CUIP5V9thWsGGFsFyGijSZf1fJMfarLHI9CEJL-TGNk
	Prefer: tx=commit
	HEAD http://postgrest/actors?actor=eq.1
	Prefer: tx=commit
	GET http://postgrest/actors?select=*,roles(*,films(*))
	Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.e30.CUIP5V9thWsGGFsFyGijSZf1fJMfarLHI9CEJL-TGNk
	Prefer: tx=commit
	POST http://postgrest/films?columns=id,title
	Prefer: tx=rollback
	@post.json
	POST http://postgrest/films?columns=id,title,year,runtime,genres,director,actors,plot,posterUrl
	Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.e30.CUIP5V9thWsGGFsFyGijSZf1fJMfarLHI9CEJL-TGNk
	Prefer: tx=rollback
	# this bulk.json was obtained from https://github.com/erik-sytnyk/movies-list/blob/master/db.json
	@bulk.json
	PUT http://postgrest/actors?actor=eq.1&columns=name
	Prefer: tx=rollback
	@put.json
	PATCH http://postgrest/actors?actor=eq.1
	Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.e30.CUIP5V9thWsGGFsFyGijSZf1fJMfarLHI9CEJL-TGNk
	Prefer: tx=rollback
	@patch.json
	DELETE http://postgrest/roles
	Prefer: tx=rollback
	GET http://postgrest/rpc/call_me?name=John
	Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.e30.CUIP5V9thWsGGFsFyGijSZf1fJMfarLHI9CEJL-TGNk
	POST http://postgrest/rpc/call_me
	@rpc.json
	OPTIONS http://postgrest/actors
	Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.e30.CUIP5V9thWsGGFsFyGijSZf1fJMfarLHI9CEJL-TGNk

More details at: #4097 (review)

Solution

Split the mixed loadtest into other loadtests by request type:

• Root openapi
• Read table (GET/HEAD)
• Read table with resource embedding
• Insert table single
• Insert table bulk
• Mutate table (PUT/PATCH)
• Delete table
• RPC GET
• RPC POST
• OPTIONS on table