[git test] convert Groovy to Java
[github] The base test class for GitHub.
IDEA-80681 Copy from IDEA in remote desktop and paste to local machine does not work
[git tests] Remove GitTestInitUtil: inline or move to GitTestUtil

Too many utility classes just for tests.
[git tests] Refactoring: move createRepository to GitTestUtil
Run local terminal in xterm mode.
Use UTF-8 charset.