Revert "Add Swift 5.5. (#3007)"
Revert "Add Swift 5.5. (#3007)"

This reverts commit 82b7249edd718c5816f7b6efd90258e26e3d5120.
Temporarily removed until we can get the swift installer/libraries working.

See compiler-explorer/infra#605
CC @Lukasa

mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer