Deprecate quic_enable_version_t051

As part of our usual version rollout, this CL removes quic_enable_version_t051 and replaces it with quic_disable_version_t051 which is marked as enabling_blocked_by.

Protected by quic_reloadable_flag_quic_disable_version_t051.

PiperOrigin-RevId: 331584508
Change-Id: I79458f6c12d35393b9c555aaefdcd6e59ad29f81
diff --git a/quic/core/quic_version_manager.cc b/quic/core/quic_version_manager.cc
index 52bb9a2..7cf6a1d 100644
--- a/quic/core/quic_version_manager.cc
+++ b/quic/core/quic_version_manager.cc
@@ -19,7 +19,7 @@
           GetQuicReloadableFlag(quic_disable_version_draft_29)),
       disable_version_draft_27_(
           GetQuicReloadableFlag(quic_disable_version_draft_27)),
-      enable_version_t051_(GetQuicReloadableFlag(quic_enable_version_t051)),
+      disable_version_t051_(GetQuicReloadableFlag(quic_disable_version_t051)),
       disable_version_t050_(GetQuicReloadableFlag(quic_disable_version_t050)),
       disable_version_q050_(GetQuicReloadableFlag(quic_disable_version_q050)),
       disable_version_q046_(GetQuicReloadableFlag(quic_disable_version_q046)),
@@ -61,7 +61,8 @@
           GetQuicReloadableFlag(quic_disable_version_draft_29) ||
       disable_version_draft_27_ !=
           GetQuicReloadableFlag(quic_disable_version_draft_27) ||
-      enable_version_t051_ != GetQuicReloadableFlag(quic_enable_version_t051) ||
+      disable_version_t051_ !=
+          GetQuicReloadableFlag(quic_disable_version_t051) ||
       disable_version_t050_ !=
           GetQuicReloadableFlag(quic_disable_version_t050) ||
       disable_version_q050_ !=
@@ -74,7 +75,7 @@
         GetQuicReloadableFlag(quic_disable_version_draft_29);
     disable_version_draft_27_ =
         GetQuicReloadableFlag(quic_disable_version_draft_27);
-    enable_version_t051_ = GetQuicReloadableFlag(quic_enable_version_t051);
+    disable_version_t051_ = GetQuicReloadableFlag(quic_disable_version_t051);
     disable_version_t050_ = GetQuicReloadableFlag(quic_disable_version_t050);
     disable_version_q050_ = GetQuicReloadableFlag(quic_disable_version_q050);
     disable_version_q046_ = GetQuicReloadableFlag(quic_disable_version_q046);
diff --git a/quic/core/quic_version_manager.h b/quic/core/quic_version_manager.h
index 8c277d7..9c742f5 100644
--- a/quic/core/quic_version_manager.h
+++ b/quic/core/quic_version_manager.h
@@ -58,8 +58,8 @@
   bool disable_version_draft_29_;
   // quic_disable_version_draft_27 flag
   bool disable_version_draft_27_;
-  // quic_enable_version_t051 flag
-  bool enable_version_t051_;
+  // quic_disable_version_t051 flag
+  bool disable_version_t051_;
   // quic_disable_version_t050 flag
   bool disable_version_t050_;
   // quic_disable_version_q050 flag
diff --git a/quic/core/quic_versions.cc b/quic/core/quic_versions.cc
index 157d2a4..c9c14a3 100644
--- a/quic/core/quic_versions.cc
+++ b/quic/core/quic_versions.cc
@@ -49,7 +49,7 @@
   } else if (version == ParsedQuicVersion::Draft27()) {
     SetQuicReloadableFlag(quic_disable_version_draft_27, disable);
   } else if (version == ParsedQuicVersion::T051()) {
-    SetQuicReloadableFlag(quic_enable_version_t051, enable);
+    SetQuicReloadableFlag(quic_disable_version_t051, disable);
   } else if (version == ParsedQuicVersion::T050()) {
     SetQuicReloadableFlag(quic_disable_version_t050, disable);
   } else if (version == ParsedQuicVersion::Q050()) {
@@ -422,7 +422,7 @@
         filtered_versions.push_back(version);
       }
     } else if (version == ParsedQuicVersion::T051()) {
-      if (GetQuicReloadableFlag(quic_enable_version_t051)) {
+      if (!GetQuicReloadableFlag(quic_disable_version_t051)) {
         filtered_versions.push_back(version);
       }
     } else if (version == ParsedQuicVersion::T050()) {