Combine `--static` and `--static-binary` (#7520)

Combine `--static` and `--static-binary` (#7520)

This PR combines the two configure flags --static and --static-binary into a single --static. Consequently, the two corresponding cmake variables are combined as well. The two variables have been implying each other for some time now and were only used to build not-completely-static binaries for MacOS, which is now done automatically anyway.