Disallow std::string_view in QUIC

This matches the C++ style guide, and is required to unblock Chrome merge because there is no implicit conversion between those two types there.

PiperOrigin-RevId: 399528944

quic/test_tools/quic_test_backend.cc

diff --git a/quic/test_tools/quic_test_backend.cc b/quic/test_tools/quic_test_backend.cc
index 288a42e..66d6769 100644
--- a/quic/test_tools/quic_test_backend.cc
+++ b/quic/test_tools/quic_test_backend.cc
@@ -45,7 +45,7 @@
     for (const auto& param : params) {
       absl::string_view param_view = param;
       if (absl::ConsumePrefix(&param_view, "set-header=")) {
-        const std::vector<std::string_view> header_value =
+        const std::vector<absl::string_view> header_value =
             absl::StrSplit(param_view, ':');
         if (header_value.size() == 2 &&
             !absl::StartsWith(header_value[0], ":")) {