When adding a presets test case, the per-case `.cmake` files are
sometimes not necessary to exercise the test logic. Relax the inclusion
of such files and remove all empty placeholders.
Note that some non-empty `CMakePresets/Trace-*.cmake` files are also
removed; they only include other empty files, and nothing in the test
case assertions (trace outputs / stderr) exercises the include
statements themselves.
Tyler Yankee
54be7af178