Unify Keystore testing tools across GFE

This CL eliminates all but one of the current N ways we configure a local Keystore instance in GFE (and Mentat) tests.  This results in the unwinding of a large amount of technical debt accreted over the last decade.

Note that there are associated changes to test certificates which can be found in the diffbase.

One notable change is the deletion of a test which checks that GFE fetches the TCP Fast Open test key.  This check is hard to implement with the local keystore tool, and I don't think the test case is useful (I also wrote it originally), so I've just deleted it.

Protected by Not protected; test changes only.

PiperOrigin-RevId: 354592197
Change-Id: Icb5eeb139a4ad8b122c3a31a6018a5d902b9bb6c
diff --git a/quic/core/crypto/crypto_server_test.cc b/quic/core/crypto/crypto_server_test.cc
index 52e00d5..a6ab228 100644
--- a/quic/core/crypto/crypto_server_test.cc
+++ b/quic/core/crypto/crypto_server_test.cc
@@ -454,7 +454,7 @@
 
 TEST_P(CryptoServerTest, RejectNotTooLarge) {
   // When the CHLO packet is large enough, ensure that a full REJ is sent.
-  chlo_packet_size_ *= 2;
+  chlo_packet_size_ *= 5;
 
   CryptoHandshakeMessage msg =
       crypto_test_utils::CreateCHLO({{"PDMD", "X509"},
diff --git a/quic/core/crypto/testdata/README.md b/quic/core/crypto/testdata/README.md
deleted file mode 100644
index 509d261..0000000
--- a/quic/core/crypto/testdata/README.md
+++ /dev/null
@@ -1,15 +0,0 @@
-# QUIC Crypto Test Data
-
-This directory contains certificates and keys used for testing QUIC. Most of the
-contents are generated by manual invocation of a script. The steps to
-regnenerate everything are:
-
-*   Build the ssl key encryptor: `blaze build
-    //gfe/gfe2/ssl_cert_storage:ssl_key_encryptor`
-
-*   Update the nonce (`nonce.txt`) to whatever stable value. If the nonce
-    changes, the process of encrypting keys must be repeated.
-
-*   Invoke the script: `go run generate.go`
-
-Make sure to commit everything to Piper when done.