Address CE CDM code review comments

Undoes a change to the buffer size from http://ag/13865723

Bug: 184813991
Test: WV unit/integration tests
Change-Id: I40cf786f149626ff65a3362020b3da859bb86159

libwvdrmengine/cdm/util/src/string_conversions.cpp

@@ -208,7 +208,7 @@ std::string b2a_hex(const std::string& byte) {
 std::string HexEncode(const uint8_t* in_buffer, size_t size) {
   static const char kHexChars[] = "0123456789ABCDEF";
   if (size == 0) return "";
-  constexpr unsigned int kMaxSafeSize = 3072;
+  constexpr unsigned int kMaxSafeSize = 2048;
   if (size > kMaxSafeSize) size = kMaxSafeSize;
   // Each input byte creates two output hex characters.
   std::string out_buffer(size * 2, '\0');