Make ast FLOGs slightly less chatty

This removes the "did_visit" message because it doesn't really add
anything.

For example:

```
ast-construction: make job_list 0x55a6d19729f0
ast-construction: make job_conjunction 0x55a6d1971c00
ast-construction: will_visit job_conjunction 0x55a6d1971c00
ast-construction:   will_visit job 0x55a6d1971c18
ast-construction:     variable_assignment_list size: 0
ast-construction:     will_visit statement 0x55a6d1971c48
ast-construction:       make decorated_statement 0x55a6d1972650
ast-construction:       will_visit decorated_statement 0x55a6d1972650
ast-construction:         make argument_or_redirection 0x55a6d1968310
ast-construction:         will_visit argument_or_redirection 0x55a6d1968310
ast-construction:           make argument 0x55a6d197b0b0
ast-construction:         did_visit argument_or_redirection 0x55a6d1968310
ast-construction:         argument_or_redirection_list size: 1
ast-construction:       did_visit decorated_statement 0x55a6d1972650
ast-construction:     did_visit statement 0x55a6d1971c48
ast-construction:     job_continuation_list size: 0
ast-construction:   did_visit job 0x55a6d1971c18
ast-construction:   job_conjunction_continuation_list size: 0
ast-construction: did_visit job_conjunction 0x55a6d1971c00
ast-construction: job_list size: 1
```

those "did_visit" messages all correspond to "will_visit" ones. They
are effectively block delimiters like `end` or `}`.

If we remove them it turns into:

```
ast-construction: make job_list 0x55a6d19729f0
ast-construction: make job_conjunction 0x55a6d1971c00
ast-construction: will_visit job_conjunction 0x55a6d1971c00
ast-construction:   will_visit job 0x55a6d1971c18
ast-construction:     variable_assignment_list size: 0
ast-construction:     will_visit statement 0x55a6d1971c48
ast-construction:       make decorated_statement 0x55a6d1972650
ast-construction:       will_visit decorated_statement 0x55a6d1972650
ast-construction:         make argument_or_redirection 0x55a6d1968310
ast-construction:         will_visit argument_or_redirection 0x55a6d1968310
ast-construction:           make argument 0x55a6d197b0b0
ast-construction:         argument_or_redirection_list size: 1
ast-construction:     job_continuation_list size: 0
ast-construction:   job_conjunction_continuation_list size: 0
ast-construction: job_list size: 1
```

Which is still unambiguous because of the indentation.

(this is still *super verbose* and we might want to remove it from the
`*` "all" debug category and only allow turning it on explicitly)

src/ast.cpp

@@ -1233,8 +1233,6 @@ class ast_t::populator_t {
         assert(!visit_stack_.empty() && visit_stack_.back() == &node &&
                "Node was not at the top of the visit stack");
         visit_stack_.pop_back();
-        FLOGF(ast_construction, L"%*sdid_visit %ls %p", spaces(), "", node.describe().c_str(),
-              (const void *)&node);
     }
 
     // The ast which we are populating.