http2/vtc: Stabilize WR_SHUT test

If a shutdown command is last in the vtc client, it closes the file descriptor
right after the shutdown, such that varnishd can not reliably send the GOAWAY,
which in turn changes the H2 error message.

Ref varnishcache#4283
Ref varnishcache#4284
Closes varnishcache#4293

Author: nigoroll

bin/varnishtest/tests/t02027.vtc

@@ -22,6 +22,12 @@ logexpect l0 -v v1 -g vxid -q "Begin ~ sess" {
 client c0 {
 	txpri
 	shutdown -write
+        stream 0 {
+		rxsettings
+                rxgoaway
+                expect goaway.laststream == 0
+                expect goaway.err == NO_ERROR
+	} -run
 } -run
 
 logexpect l1 -v v1 -g vxid -q "Begin ~ sess" {
@@ -40,6 +46,11 @@ client c1 {
 		txreq -nohdrend
 	} -run
 	shutdown -write
+        stream 0 {
+                rxgoaway
+                expect goaway.laststream == 1
+                expect goaway.err == NO_ERROR
+	} -run
 } -run
 
 logexpect l2 -v v1 -g vxid -q "Begin ~ sess" {
@@ -58,6 +69,11 @@ client c2 {
 		txreq -nostrend
 	} -run
 	shutdown -write
+        stream 0 {
+                rxgoaway
+                expect goaway.laststream == 1
+                expect goaway.err == NO_ERROR
+	} -run
 } -run
 
 logexpect l3 -v v1 -g vxid -q "Begin ~ sess" {
@@ -85,6 +101,11 @@ client c3 {
 		#	00053a70617468012f00073a6d6574686f640347455400073a736368656d650468747470
 	} -run
 	shutdown -write
+        stream 0 {
+                rxgoaway
+                expect goaway.laststream == 0
+                expect goaway.err == NO_ERROR
+	} -run
 } -run
 
 logexpect l0 -wait