ci: Upload failed MacVim tests artifacts, misc improvements #793

Job	Run time
build-and-test (macos-13, 15.2, vimtags, check-xcodeproj-compat)	40m 31s
build-and-test (macos-13, 15.2, vimtags, check-xcodeproj-compat)	40m 31s
build-and-test (macos-14, 15.4, true)	36m 21s
build-and-test (macos-14, 15.4, true)	36m 21s
build-and-test (macos-15, 16.2, true, true)	27m 26s
build-and-test (macos-15, 16.2, true, true)	11m 50s
	3h 13m 0s

Provide feedback