Remove obsolete string-like constructors for Item

All callers have been migrated to the less error-prone tag-based constructors.

PiperOrigin-RevId: 983851272

quiche/common/structured_headers.cc

diff --git a/quiche/common/structured_headers.cc b/quiche/common/structured_headers.cc
index fed44e1..7567388 100644
--- a/quiche/common/structured_headers.cc
+++ b/quiche/common/structured_headers.cc
@@ -812,24 +812,6 @@
 }
 
 Item::Item() = default;
-Item::Item(std::string value, Item::ItemType type) {
-  switch (type) {
-    case kStringType:
-      value_.emplace<std::string>(std::move(value));
-      break;
-    case kTokenType:
-      value_.emplace<Token>(std::move(value));
-      break;
-    case kByteSequenceType:
-      value_.emplace<ByteSequence>(std::move(value));
-      break;
-    default:
-      QUICHE_CHECK(false);
-      break;
-  }
-}
-Item::Item(const char* value, Item::ItemType type)
-    : Item(std::string(value), type) {}
 Item::Item(int64_t value) : value_(value) {}
 Item::Item(double value) : value_(value) {}
 Item::Item(bool value) : value_(value) {}

quiche/common/structured_headers.h

diff --git a/quiche/common/structured_headers.h b/quiche/common/structured_headers.h
index 0d8645f..55a6b96 100644
--- a/quiche/common/structured_headers.h
+++ b/quiche/common/structured_headers.h
@@ -108,12 +108,6 @@
   Item(byte_sequence_t, absl::string_view value);
   Item(byte_sequence_t, std::string value);
 
-  // Constructors for string-like items: Strings, Tokens and Byte Sequences.
-  // Deprecated: Use one of the tag-based constructors with `Item::string`,
-  // `Item::token`, or `Item::byte_sequence` instead.
-  Item(const char* value, Item::ItemType type = kStringType);
-  Item(std::string value, Item::ItemType type = kStringType);
-
   Item(const Item&);
   Item& operator=(const Item&);