roachprod: fix node environment variable propagation

In cockroachdb#67363, configured environment variables were no longer
propagated to nodes. In particular, the default node envvar
`COCKROACH_ENABLE_RPC_COMPRESSION=false` was not passed,
which caused a 5% performance regression on certain benchmarks.

This patch fixes propagation of environment variables.

Release note: None

pkg/cmd/roachprod/install/cluster_synced.go

@@ -69,7 +69,7 @@ type SyncedCluster struct {
 	Nodes          []int
 	Secure         bool
 	CertsDir       string
-	Env            string
+	Env            []string
 	Args           []string
 	Tag            string
 	Impl           ClusterImpl

pkg/cmd/roachprod/install/cockroach.go

@@ -436,10 +436,10 @@ func (h *crdbInstallHelper) generateStartCmd(
 		LogDir: h.c.Impl.LogDir(h.c, nodes[nodeIdx]),
 		KeyCmd: h.generateKeyCmd(nodeIdx, extraArgs),
 		Tag:    h.c.Tag,
-		EnvVars: append([]string{
+		EnvVars: append(append([]string{
 			"GOTRACEBACK=crash",
 			"COCKROACH_SKIP_ENABLING_DIAGNOSTIC_REPORTING=1",
-		}, h.getEnvVars()...),
+		}, h.c.Env...), h.getEnvVars()...),
 		Binary:           cockroachNodeBinary(h.c, nodes[nodeIdx]),
 		StartCmd:         startCmd,
 		Args:             args,

pkg/cmd/roachprod/main.go

@@ -185,7 +185,7 @@ Available clusters:
 	c.Nodes = nodes
 	c.Secure = secure
 	c.CertsDir = certsDir
-	c.Env = strings.Join(nodeEnv, " ")
+	c.Env = nodeEnv
 	c.Args = nodeArgs
 	if tag != "" {
 		c.Tag = "/" + tag