test/e2e: add random testnet generator (#5479)

Closes #5291. Adds a randomized testnet generator. Nightly CI job will be submitted separately. A few of the testnets can be a bit flaky, even after disabling known-faulty behavior and making minor tweaks, and the larger networks may be too resource-intensive to run in CI - this will be optimized separately.

test/e2e/app/config.go

@@ -1,3 +1,4 @@
+//nolint: goconst
 package main
 
 import (

test/e2e/app/main.go

@@ -45,6 +45,17 @@ func run(configFile string) error {
 		return err
 	}
 
+	// Start remote signer (must start before node if running builtin).
+	if cfg.PrivValServer != "" {
+		if err = startSigner(cfg); err != nil {
+			return err
+		}
+		if cfg.Protocol == "builtin" {
+			time.Sleep(1 * time.Second)
+		}
+	}
+
+	// Start app server.
 	switch cfg.Protocol {
 	case "socket", "grpc":
 		err = startApp(cfg)
@@ -57,13 +68,6 @@ func run(configFile string) error {
 		return err
 	}
 
-	// Start remote signer
-	if cfg.PrivValServer != "" {
-		if err = startSigner(cfg); err != nil {
-			return err
-		}
-	}
-
 	// Apparently there's no way to wait for the server, so we just sleep
 	for {
 		time.Sleep(1 * time.Hour)