TASK: Clean up .gitattributes and .gitignore

1. Sort entries by name.
2. Remove redundant "/nbproject/" and "/nbproject/private/".
3. Remove outdated "/build/logs/", "/cache/", "/debug/".

.gitattributes

@@ -2,8 +2,8 @@
 .github export-ignore
 build export-ignore
 tests export-ignore
-demo.php export-ignore
 .gitattributes export-ignore
 .gitignore export-ignore
+demo.php export-ignore
 index.html export-ignore
 phpunit.xml export-ignore

.gitignore

@@ -1,8 +1,6 @@
-/.idea
-/nbproject/private/
-/build/logs/
-/cache/
+.phpunit.result.cache
+
+/.idea/
 /nbproject/
-/debug/
-/composer.lock
 /vendor/
+/composer.lock