[clang] [Driver] Remove ignored Flag form of -fauto-profile/-fprofile-sample-use (PR #113528)

[Fangrui Song via cfe-commits]

MaskRay wrote:

> Regarding the default filename extension, it doesn't have to be `.profdata` for `fprofile-sample-use`, it can be the `.afdo`, or any other extension deemed proper. `fprofile-sample-use` and `fprofile-use` would behave similarly then: they would look for a `default` file with appropriate extension, which seems like a reasonable behavior to me

I respectively disagree. The sample PGO framework is quite different from instrumentation PGO. There is no `-fprofile-sample-generate`. While the naming `-fprofile-sample-use=` is similar to `-fprofile-use=`, it's a very weak argument to have a default filename, when the filename in the wild has many uses of very different extensions.

The deployment experience has shown that we don't really need a default filename.

https://github.com/llvm/llvm-project/pull/113528