[FIX] OWScatterPlotBase: Reset view before labels update

[VesnaT]

Issue

In some cases labels on projection widgets are deficiently shown.
To reproduce:

1. File (brown-selected) -> Preprocess -> MDS
2. MDS: Set Label to Genes
3. Preprocess (Select Normalize Features)
4. MDS: All labels are show
5. Preprocess (Remove normalizer)
6. MDS: Some labels (close to left and upper edge) are missing

Description of changes

Reset view before updating the labels.

Includes

• Code changes
• Tests
• Documentation

[codecov]

Codecov Report

Merging #4907 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           master    #4907    +/-   ##
========================================
  Coverage   84.12%   84.13%            
========================================
  Files         283      278     -5     
  Lines       57819    57007   -812     
========================================
- Hits        48643    47961   -682     
+ Misses       9176     9046   -130