Fix deprecated methods from #4620

[matusvalo]

Steps

• Add yourself to CONTRIBUTORS if you are a new contributor.
• Add a ChangeLog entry describing what your PR does.
• If it's a new feature or an important bug fix, add a What's New entry in
  doc/whatsnew/<current release.rst>.
• Write a good description on what the PR does.

Description

Fixes several issues in #4620:

• Remove duplicates
• Remove SSLSocket methods - the methods cannot be inferred when created by factory SSLContext.wrap_socket
• ssl.RAND_pseudo_bytes -> _ssl.RAND_pseudo_bytes

Type of Changes

	Type
✓	🐛 Bug fix
	✨ New feature
	🔨 Refactoring
	📜 Docs

Related Issue

[Pierre-Sassoulas]

We basically released 2.9.0 just after merging #4620, I hope it's not too problematic, but we can release 2.9.1 fast if it is :)

[cdce8p]

@Pierre-Sassoulas We can merge this but lets's just wait and see if we get any bug reports about it before doing a hotfix release. As I understand it, those are only minor things so we might not even get one about it.

[coveralls]

Coverage remained the same at 92.041% when pulling 410f180 on matusvalo:stdlib_fix into 52027cb on PyCQA:master.

[matusvalo]

@Pierre-Sassoulas there is still one problem:
Pylint is having problem with zipimport.zipimporter not sure why:

(pylint38) matus@home:~/dev/pylint$ cat test.py
import zipimport
zipimport.zipimporter('/path/to/zip').load_module()

matus@home:~/dev/pylint$ python test.py                                     
Traceback (most recent call last):
  File "<frozen zipimport>", line 75, in __init__
  File "<frozen importlib._bootstrap_external>", line 87, in _path_stat
FileNotFoundError: [Errno 2] No such file or directory: ''

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "test.py", line 45, in <module>
    zipimport.zipimporter('/path/to/zip').load_module()
  File "<frozen zipimport>", line 81, in __init__
zipimport.ZipImportError: not a Zip file

(pylint38) matus@home:~/dev/pylint$ pylint test.py
************* Module test
test.py:45:0: E1101: Module 'zipimport' has no 'zipimporter' member (no-member)

----------------------------------------------------------------------
Your code has been rated at -15.00/10 (previous run: -15.00/10, +0.00)

Running script crashes because of dummy parameters but zipimporter exists
pylint is saying that module has no member :-( and skips checking of deprecated method (checked with pdb)

[matusvalo]

Doublechecked now, deprecation is not checked due issues with inferrence error in line:
https://github.com/PyCQA/pylint/blob/0f6a38ee54362ae2e4f5f294f26942261d61485e/pylint/checkers/deprecated.py#L63

*** astroid.exceptions.InferenceError: Inference failed for <Attribute.zipimporter l.45 at 0x7fec302fe220>.

[Pierre-Sassoulas]

I think #4631 might be the same problem ? It's not the same problem.