[TVMScript] More concise T.allocate syntax printing (apache#13830)

This PR is the follow up of apache#13813. We simplify the printing output of `T.allocate` with `T.decl_buffer`. For example, we have a code snippet as 

```python
buffer_data = T.allocate(...)
buffer = T.decl_buffer(..., data=buffer_data)
T.evaluate(buffer_data)
```

Originally, we skip the `T.allocate` only if the var `buffer_data` defined by `T.allocate` is used only once by the following `T.decl_buffer`. This was due to the limitation of the old printer design. 

But in the new printer, we may automatically replace the `buffer_data` with `buffer.data` if skipping the definition of `buffer_data`. We are able to link all `buffer_data` usages together. So the new output result will be like

```python
buffer = T.decl_buffer(...)
T.evaluate(buffer.data)
```

src/script/printer/tir/stmt.cc

@@ -175,9 +175,7 @@ TVM_STATIC_IR_FUNCTOR(IRDocsifier, vtable)
     .set_dispatch<tir::Allocate>(  //
         "", [](tir::Allocate stmt, ObjectPath stmt_p, IRDocsifier d) -> Doc {
           bool concise = AllowConciseScoping(d);
-          OccurrenceCounter counter(stmt->buffer_var.get());
-          counter(stmt->body);
-          if (counter.count == 1 && IsAllocateDeclBufferPattern(stmt.get())) {
+          if (IsAllocateDeclBufferPattern(stmt.get())) {
             return d->AsDoc(stmt->body, stmt_p->Attr("body"));
           }
           Array<ExprDoc> args;

tests/python/unittest/test_tvmscript_printer_tir.py

@@ -343,7 +343,7 @@ def test_allocate_with_decl_buffer_sugar():
     )
 
 
-def test_allocate_with_decl_buffer_no_sugar_multi_usage():
+def test_allocate_with_decl_buffer_sugar_multi_usage():
     with IRBuilder() as ib:
         with T.allocate([128, 128], "float32") as buffer_data:
             with T.decl_buffer([128, 128], "float32", data=buffer_data) as buffer:
@@ -352,9 +352,8 @@ def test_allocate_with_decl_buffer_no_sugar_multi_usage():
     _assert_print(
         obj,
         """
-with T.allocate([128, 128], "float32", "global") as v:
-    buffer = T.decl_buffer((128, 128), data=v)
-    T.evaluate(v)
+with T.decl_buffer((128, 128)) as buffer:
+    T.evaluate(buffer.data)
 """,
     )