runner: Remove unused SendHalfRTTData option

I forget why we added this. It looks like it's never actually been used.
Half-RTT vs 1-RTT data is not distinguishable from the client, so I
suspect we never actually need to simulate it in the test runner.

Change-Id: I851e2caf417d00da654ee530a240ce54af1415d4
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/72888
Reviewed-by: Nick Harper <nharper@chromium.org>
Commit-Queue: David Benjamin <davidben@google.com>

ssl/test/runner/common.go

diff --git a/ssl/test/runner/common.go b/ssl/test/runner/common.go
index 462172a..0c54593 100644
--- a/ssl/test/runner/common.go
+++ b/ssl/test/runner/common.go
@@ -1711,11 +1711,6 @@
 	// the number of records or their content do not match.
 	ExpectLateEarlyData [][]byte
 
-	// SendHalfRTTData causes a TLS 1.3 server to send the provided
-	// data in application data records before reading the client's
-	// Finished message.
-	SendHalfRTTData [][]byte
-
 	// ExpectHalfRTTData causes a TLS 1.3 client, if 0-RTT was accepted, to
 	// read application data after reading the server's Finished message and
 	// before sending any subsequent handshake messages. It checks that the

ssl/test/runner/handshake_server.go

diff --git a/ssl/test/runner/handshake_server.go b/ssl/test/runner/handshake_server.go
index 08165ae..799eb13 100644
--- a/ssl/test/runner/handshake_server.go
+++ b/ssl/test/runner/handshake_server.go
@@ -1252,13 +1252,6 @@
 	// from the client certificate are sent over these keys.
 	c.useOutTrafficSecret(uint16(encryptionApplication), c.wireVersion, hs.suite, serverTrafficSecret)
 
-	// Send 0.5-RTT messages.
-	for _, halfRTTMsg := range config.Bugs.SendHalfRTTData {
-		if _, err := c.writeRecord(recordTypeApplicationData, halfRTTMsg); err != nil {
-			return err
-		}
-	}
-
 	// Read end_of_early_data.
 	if encryptedExtensions.extensions.hasEarlyData && c.usesEndOfEarlyData() {
 		msg, err := c.readHandshake()