service: plumb contexts to all (most) threads (#7363)

This continues the push of plumbing contexts through tendermint. I
attempted to find all goroutines in the production code (non-test) and
made sure that these threads would exit when their contexts were
canceled, and I believe this PR does that.

test/e2e/node/main.go

@@ -246,6 +246,10 @@ func startSigner(ctx context.Context, cfg *Config) error {
 			if err := s.Serve(lis); err != nil {
 				panic(err)
 			}
+			go func() {
+				<-ctx.Done()
+				s.GracefulStop()
+			}()
 		}()
 
 		return nil

test/e2e/runner/main.go

@@ -319,8 +319,7 @@ Does not run any perbutations.
 			lctx, loadCancel := context.WithCancel(ctx)
 			defer loadCancel()
 			go func() {
-				err := Load(lctx, r, cli.testnet)
-				chLoadResult <- err
+				chLoadResult <- Load(lctx, r, cli.testnet)
 			}()
 
 			if err := Start(ctx, cli.testnet); err != nil {