Prevent duplicate filterByTruthyValue() work in NodeScopeResolver

[staabm]

with polluteScopeWithAlwaysIterableForeach: true

before this PR:

➜  phpstan-src git:(2.2.x) ✗ hyperfine 'php bin/phpstan analyze src/Analyser/MutatingScope.php -v --debug' -i --runs=5
Benchmark 1: php bin/phpstan analyze src/Analyser/MutatingScope.php -v --debug
  Time (mean ± σ):      2.241 s ±  0.180 s    [User: 1.948 s, System: 0.287 s]
  Range (min … max):    2.104 s …  2.539 s    5 runs

after this PR:

➜  phpstan-src git:(2.2.x) ✗ hyperfine 'php bin/phpstan analyze src/Analyser/MutatingScope.php -v --debug' -i --runs=5
Benchmark 1: php bin/phpstan analyze src/Analyser/MutatingScope.php -v --debug
  Time (mean ± σ):      2.101 s ±  0.021 s    [User: 1.835 s, System: 0.260 s]
  Range (min … max):    2.081 s …  2.132 s    5 runs

[staabm]

shipmonk/dead-code-detector breakage is unrelated, see #6098 (comment)

[phpstan-bot]

This pull request has been marked as ready for review.