[memprof] Make RecordWriterTrait a non-template class (#87604)

commit d89914f3
  Author: Kazu Hirata <kazu@google.com>
  Date:   Wed Apr 3 21:48:38 2024 -0700

changed RecordWriterTrait to a template class with IndexedVersion as a
template parameter.  This patch changes the class back to a
non-template one while retaining the ability to serialize multiple
versions.

The reason I changed RecordWriterTrait to a template class was
because, even if RecordWriterTrait had IndexedVersion as a member
variable, RecordWriterTrait::EmitKeyDataLength, being a static
function, would not have access to the variable.

Since OnDiskChainedHashTableGenerator calls EmitKeyDataLength as:

  const std::pair<offset_type, offset_type> &Len =
      InfoObj.EmitKeyDataLength(Out, I->Key, I->Data);

we can make EmitKeyDataLength a member function, but we have one
problem.  InstrProfWriter::writeImpl calls:

  void insert(typename Info::key_type_ref Key,
              typename Info::data_type_ref Data) {
    Info InfoObj;
    insert(Key, Data, InfoObj);
  }

which default-constructs RecordWriterTrait without a specific version
number.  This patch fixes the problem by adjusting
InstrProfWriter::writeImpl to call the other form of insert instead:

  void insert(typename Info::key_type_ref Key,
              typename Info::data_type_ref Data, Info &InfoObj)

To prevent an accidental invocation of the default constructor of
RecordWriterTrait, this patch deletes the default constructor.