Investigate -fsanitize=cfi and -flto on Clang Linux builds

[RossBrunton]

We would like to run -fsanitize=cfi as part of our clang builds. However, it requires -flto optimization to be enabled, which causes a number of failures (e.g. #2105 ), and makes our test suite run in a non-deterministic order.

We should either fix all of those issues, find a way to run -fsanitize=cfi without -flto or decide we don't want to enable it.

[RossBrunton]

#2222 This change doesn't fix all the issues, but it did result in followup tickets being created:

• -flto -fsanitize=cfi causes linker errors on the CI fuzz testing job #2323
• -flto -fsanitize=cfi cause issues on the CUDA CI node #2309
• Level Zero V2 level_zero_event_pool tests fail with SIGILL when the CFI sanitizer is enabled #2324

Closing this ticket since we have the flags mostly working and the non-deterministic test ordering has been solved.