fix(Makefile): gofumpt no longer needed (#2235)

It looks like `go generate -run="./scripts/mockery_generate.sh" ./...`
produces correctly formatted (from `gofumpt` perspective) output.

Closes #2212

Makefile

@@ -112,7 +112,6 @@ testdata-metrics:
 #? mockery: Generate test mocks
 mockery:
 	go generate -run="./scripts/mockery_generate.sh" ./...
-	@go run mvdan.cc/gofumpt@latest -l -w .
 .PHONY: mockery
 
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