pkg/fileutils: TestMatches: remove cases no longer valid for go1.16
pkg/fileutils: TestMatches: remove cases no longer valid for go1.16

These tests were no longer valid on Go 1.16; related to https://tip.golang.org/doc/go1.16#path/filepath

> The Match and Glob functions now return an error if the unmatched part of
> the pattern has a syntax error. Previously, the functions returned early on
> a failed match, and thus did not report any later syntax error in the pattern.

Causing the test to fail:

    === RUN   TestMatches
        fileutils_test.go:388: assertion failed: error is not nil: syntax error in pattern: pattern="a\\" text="a"
    --- FAIL: TestMatches (0.00s)

Signed-off-by: Sebastiaan van Stijn <64b2b6d12bfe4baae7dad3d018f8cbf6b0e7a044@gone.nl>

vdemeester/docker,yosifkit/docker,paralin/docker,gnailuy/docker,thaJeztah/docker,AkihiroSuda/docker,thaJeztah/docker,Ramzec/docker,moul/docker,paralin/docker,mahak/docker,cpuguy83/docker,jimjag/docker,moby/moby,paralin/docker,djs55/docker,Ramzec/docker,flavio/docker,AkihiroSuda/docker,mahak/docker,djs55/docker,mahak/docker,cpuguy83/docker,jthelin/docker,nalind/docker,konstruktoid/docker-upstream,yosifkit/docker,Mokolea/docker,cpuguy83/docker,docker/docker,konstruktoid/docker-upstream,jimjag/docker,bearstech/moby,nawawi/docker,yosifkit/docker,paralin/docker,bearstech/moby,moby/moby,Mokolea/docker,trebonian/docker,vdemeester/docker,jimjag/docker,konstruktoid/docker-upstream,jthelin/docker,flavio/docker,jameszhan/docker,konstruktoid/docker-upstream,nawawi/docker,nalind/docker,bearstech/moby,jameszhan/docker,Mokolea/docker,nawawi/docker,Mokolea/docker,jameszhan/docker,trebonian/docker,mahak/docker,nalind/docker,docker/docker,nawawi/docker,nalind/docker,jimjag/docker,gnailuy/docker,trebonian/docker,flavio/docker,moby/moby,docker/docker,flavio/docker,trebonian/docker,moul/docker,thaJeztah/docker,moul/docker,cpuguy83/docker,gnailuy/docker,AkihiroSuda/docker,bearstech/moby,yosifkit/docker,Ramzec/docker,gnailuy/docker,moby/moby,AkihiroSuda/docker,Ramzec/docker,moul/docker,vdemeester/docker,thaJeztah/docker,djs55/docker