refactor: use uniform example file names #56

Job	Run time
setup	25s
simple-build	12s
simple-build (-skip-unused)	10s
lint / fmt	11s
test	12s
setup-clang	41s
different-compilers (gcc)	22s
different-compilers (gcc, -prod)	45s
different-compilers (gcc, -skip-unused)	29s
different-compilers (gcc, -skip-unused, -prod)	34s
different-compilers (clang)	45s
different-compilers (clang, -prod)	52s
different-compilers (clang, -skip-unused)	44s
different-compilers (clang, -skip-unused, -prod)	1m 2s
gcc-address-sanitizers	43s
clang-sanitizers (address)	1m 1s
clang-sanitizers (memory)	1m 6s
clang-sanitizers (undefined)	54s
clang-sanitizers (leak)	53s
gcc-undefined-sanitizers	31s
gcc-sanitizers (leak)	21s
	12m 53s

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