Avoid left join when filtering for channel permissions

[jredrejo]

Description

filter_view_queryset was adding a left join on Invitations that was causing duplicated results when showing a list of channels.
This pr replaces the used query using only the list of pending invitations the user has.
In any case I wonder if we should show to the user channels that have pending invitations

By the way: this issue hadn't been seen before because admins don't have this problem and most of LE staff are admins when testing Studio

Issue Addressed (if applicable)

Closes#2899

Before/After Screenshots (if applicable)

Documented in the refered issue

Steps to Test

Login as a non-admin user
Look at the list of channels and check there are not repated channels in the list

[codecov]

Codecov Report

Merging #2948 (c88820e) into hotfixes (28587f8) will increase coverage by 4.78%.
The diff coverage is 93.00%.

@@ Coverage Diff @@## hotfixes #2948 +/- ##
============================================
+ Coverage 80.80% 85.58% +4.78% 
============================================
Files 281 299 +18 Lines 12659 15887 +3228 ============================================
+ Hits 10229 13597 +3368 + Misses 2430 2290 -140 

Impacted Files	Coverage Δ
contentcuration/contentcuration/decorators.py	56.60% <50.00%> (-37.60%)	⬇️
...ntentcuration/contentcuration/db/models/manager.py	91.20% <90.98%> (-8.80%)	⬇️
contentcuration/contentcuration/forms.py	82.85% <94.31%> (+34.40%)	⬆️
contentcuration/contentcuration/api.py	92.06% <100.00%> (+1.43%)	⬆️
...tentcuration/contentcuration/context_processors.py	100.00% <100.00%> (ø)
...ontentcuration/contentcuration/db/advisory_lock.py	100.00% <100.00%> (ø)
...tcuration/contentcuration/db/models/expressions.py	93.33% <100.00%> (-6.67%)	⬇️
...entcuration/contentcuration/db/models/functions.py	100.00% <100.00%> (ø)
...ation/contentcuration/tests/test_rest_framework.py	36.93% <0.00%> (-63.07%)	⬇️
contentcuration/contentcuration/utils/format.py	21.05% <0.00%> (-49.54%)	⬇️
... and 181 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3fdaf7c...3ff36de. Read the comment docs.