Remove floc header

[Houdini]

1. floc header is obsolete
2. Condition is wrong anyway, it should be == instead of !==

[Houdini]

@bryannielsen Hello, could you please check that PR. Is these tests are really necessary?
They probably failed because of my old branch, can we ignore that?

[bryannielsen]

@Houdini it looks like the new Topics API that replaced FLoC still respects this header to "opt out of user tracking for interest-based advertising". The logic looks correct based on the docs but I see that a similar request was made to remove the header from the core which is where this particular code came from so I think we can move this forward.

It looks like the Laravel 9 tests are failing because of an issue composer audit found. I think we can add the ignore rule for this because any security issues with Laravel 9 are a concern for the user but not our tests.