lint: address fixme / W0511

There are a few occurrences where code is being used to keep track of
possible improvements.  Many times these will go unnoticed for ages.

Let's either document the limitations that are affected by the
"TODO"s, or remove them because after quite some time, they were not
something that was attempted to be improved or fixed.

https://pylint.pycqa.org/en/latest/user_guide/messages/warning/fixme.html
Signed-off-by: Cleber Rosa <[email protected]>

.pylintrc_utils

@@ -119,8 +119,7 @@ disable=C0103,
   R1729,
   R1730,
   R1732,
-  W0212,
-  W0511
+  W0212
 
 [REPORTS]
 

avocado/utils/lv_utils.py

@@ -311,7 +311,6 @@ def vg_list(vg_name=None):
         lines = lines[1:]
     else:
         return vgroups
-    # TODO: Optimize this
     for line in lines:
         details = line.split()
         details_dict = {}

avocado/utils/process.py

@@ -295,9 +295,11 @@ def process_in_ptree_is_defunct(ppid):
     Attempt to verify if parent process and any children from PPID is defunct
     (zombie) or not.
 
+    This relies on the GNU version of "ps" and is not guaranteed to work in
+    MacOS.
+
     :param ppid: The parent PID of the process to verify.
     """
-    # TODO: This relies on the GNU version of ps (need to fix MacOS support)
     defunct = False
     try:
         pids = get_children_pids(ppid)
@@ -455,9 +457,6 @@ def __init__(
         self.fd = fd
         self.name = name
         self.data = BytesIO()
-        # TODO: check if, when the process finishes, the FD doesn't
-        # automatically close.  This may be used as the detection
-        # instead.
         self._result = result
         self._thread = None
         self._logger = logger