[lit] Move maxIndividualTestTime from global to test suite config (#198192)
Simplify LitConfig initialization and setter to allow None values.
TestingConfig.maxIndividualTestTime is initialized to 0 (or resolved to
0 if None) strictly during initialization.
This fixes an issue where the aggressive BOLT timeout of 60s (previously
set globally on lit_config) was leaking and affecting libc++ tests. By
moving the timeout configuration from the global lit_config to the
individual test suite config, we ensure that timeouts are isolated and
respect suite-local settings without leaking.
PR Stack:
* ➤ https://github.com/llvm/llvm-project/pull/198192
* https://github.com/llvm/llvm-project/pull/198193
Assisted-by: Gemini