Fix clang-tidy performance warnings in syste/core.

* Use const reference type for parameters to avoid unnecessary copy.
* Suppress warning of not using faster overloaded string find function.

Bug: 30407689
Bug: 30411878
Change-Id: Ie79dbe21899867bc62031f8618bb1322b8071525
Test: build with WITH_TIDY=1
10 files changed