SQIL and PC performance check fixes

[ernestum]

Description

• Speeds up SQIL tests by decreasing the number of training steps
• Skips SQIL performance tests because they are flaky
• Adds some more seeds to SQIL tests
• Fixes failing preference comparison performance test by increasing number of training steps and the number of samples to compare trained and novice agent.

Fixes #807 Fixes #791

Testing

Changes are covered by the existing tests.

[codecov[bot]]

Codecov Report

Merging #811 (1b20336) into master (20366b0) will decrease coverage by 0.05%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #811      +/-   ##
==========================================
- Coverage   95.67%   95.63%   -0.05%     
==========================================
  Files         100      100              
  Lines        9581     9582       +1     
==========================================
- Hits         9167     9164       -3     
- Misses        414      418       +4     

Files	Coverage Δ
tests/algorithms/test_preference_comparisons.py	100.00% <100.00%> (ø)
tests/algorithms/test_sqil.py	93.67% <100.00%> (-6.33%)	:arrow_down:

... and 1 file with indirect coverage changes

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[ernestum]

Hi @AdamGleave would you review and merge? The coverage went down since I disabled the SQIL performance tests for now.