legacy tests: migrate test7

src/nvim/testdir/test7.in

@@ -1,26 +0,0 @@
-Test for autocommand that changes the buffer list, when doing ":ball".
-
-STARTTEST
-:so small.vim
-/^start of
-A1:.,/end of/w! Xxx1   " write test file Xxx1
-:sp Xxx1
-:close
-$r2:.,/end of/w! Xxx2    " write test file Xxx2
-:sp Xxx2
-:close
-$r3:.,/end of/w! Xxx3    " write test file Xxx3
-:sp Xxx3
-:close
-:au BufReadPost Xxx2 bwipe
-$r4:ball                 " open window for all args, close Xxx2
-:.,$w! test.out          " Write contents of this file
-:w >>test.out        " Append contents of second window (Xxx1)
-:/^start of/,$w >>test.out   " Append contents of last window (this file)
-:qa!
-ENDTEST
-
-start of test file Xxx
-	this is a test
-	this is a test
-end of test file Xxx

src/nvim/testdir/test7.ok

@@ -1,12 +0,0 @@
-start of test file Xxx4
-	this is a test
-	this is a test
-end of test file Xxx
-start of test file Xxx1
-	this is a test
-	this is a test
-end of test file Xxx
-start of test file Xxx4
-	this is a test
-	this is a test
-end of test file Xxx