Use self:: over $this-> for PHPUnit assertions

[staabm]

with static calls assertion-calls do not affect remembered non-static properties.

in addition assertion methods are declared static so we don't need to process ignored errors for these lines

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before PR

➜  phpstan-src git:(2.1.x) ✗ hyperfine 'bin/phpstan analyze tests/PHPStan/Analyser/AnalyserIntegrationTest.php' --runs=5
Benchmark 1: bin/phpstan analyze tests/PHPStan/Analyser/AnalyserIntegrationTest.php
  Time (mean ± σ):      2.537 s ±  0.047 s    [User: 2.224 s, System: 0.279 s]
  Range (min … max):    2.508 s …  2.620 s    5 runs

after PR

➜  phpstan-src git:(this-self) ✗ hyperfine 'bin/phpstan analyze tests/PHPStan/Analyser/AnalyserIntegrationTest.php' --runs=5
Benchmark 1: bin/phpstan analyze tests/PHPStan/Analyser/AnalyserIntegrationTest.php
  Time (mean ± σ):      2.526 s ±  0.016 s    [User: 2.220 s, System: 0.281 s]
  Range (min … max):    2.513 s …  2.554 s    5 runs

[ondrejmirtes]

I kind of disagree with this one. PHPUnit documentation allows both, and because of years of muscle memory I still use $this-> myself.

If anything we should have ignoreErrors entry with reportUnmatched: false in phpstan-phpunit so that people don't have to ignore this on their own. Or an IgnoreErrorsExtension.