gitignore: add enterprise-tap

Follow-up commit https://github.com/tarantool/tarantool-ee/commit/40627acae33cd8b4fee096c6197c3bd3d124b4a4
("test: move Lua tests from /static-build/test to /test/enterprise-tap")

NO_DOC=gitignore
NO_TEST=gitignore
NO_CHANGELOG=gitignore