Remove unnecessary method calls in ClassReflection

[staabm]

drive-by cleanups while analyzing the cause of phpstan/phpstan#10772

[staabm]

before this PR:

$ time vendor/bin/phpstan analyse --debug
Note: Using configuration file C:\dvl\Workspace\stan-long\phpstan.neon.
C:\dvl\Workspace\stan-long\src\test.php


 [OK] No errors



real    2m8.411s
user    0m0.000s
sys     0m0.000s

after the 2 commits

$ time ../phpstan-src/bin/phpstan analyse --debug
Note: Using configuration file C:\dvl\Workspace\stan-long\phpstan.neon.
C:\dvl\Workspace\stan-long\src\test.php


 [OK] No errors



real    1m16.387s
user    0m0.000s
sys     0m0.015s

not perfect but waaay faster. still investigating..

[ondrejmirtes]

Thank you!