Make the CI check the indent on most of the unit tests

There were two `--exclude` statements both pointing at the data/test
directory before, which was a trivial bug.

Exclude cve_tests because of the binary file that's masquerading as a .cfg;
I think it's correct to exclude the whole directory because any new tests
added there might also use weird edge cases in the parsing.

Exclude lua_tests as a "keep this PR small" thing. We should fix the bugs in
wmlindent, but I don't want to take on that work.

The exclusion of TerrainWML is again because I don't want to take on the work
of working out whether it's problems with terrain masks or bugs in wmlindent.

Most of the files in those directories wouldn't be changed, the ones that would
(or would trigger an error about not being valid UTF-8 ) are:

* data/test/scenarios/cve_tests/test_cve_2018_1999023_2.cfg
* data/test/scenarios/lua_tests/functional/lua_functional.cfg
* data/test/scenarios/lua_tests/wesnoth/map/mapgen_filter.cfg
* data/test/scenarios/wml_tests/TerrainWML/test_terrain_mask.cfg

data/tools/Makefile

@@ -71,7 +71,14 @@ unchecked:
 
 # Reindent the mainline content
 reindent:
-	@./wmlindent --exclude=../../data/languages --exclude=../../data/gui --exclude=../../data/test  --exclude=../../data/test  --exclude=../../data/schema $(DATA)
+	@./wmlindent \
+		--exclude=../../data/languages \
+		--exclude=../../data/gui \
+		--exclude=../../data/test/scenarios/cve_tests \
+		--exclude=../../data/test/scenarios/lua_tests \
+		--exclude=../../data/test/scenarios/wml_tests/TerrainWML \
+		--exclude=../../data/schema \
+		$(DATA)
 
 # Extract a table of editor keybindings from the editor theme definition
 editor_bindings: