Highlighting: undo broken languages

Highlighthing is timing out for Ruby, C++, and Python, on
sourcegraph.com because we're trying to highlight these languages with
tree-sitter when syntax-highlighter has no tree-sitter support for those
languages. The grammars for these languages depend on C++ code that we weren't
able to build in CI so we removed them last minute before merging
the PR that added tree-sitter highligting for Java, TypeScript,
JavaScript, and Rust. https://github.com/sourcegraph/sourcegraph/pull/47571

Author: olafurpg

cmd/frontend/internal/highlight/language.go

@@ -108,14 +108,10 @@ var baseEngineConfig = syntaxEngineConfig{
 		"jsx":        EngineTreeSitter,
 		"typescript": EngineTreeSitter,
 		"tsx":        EngineTreeSitter,
-		"python":     EngineTreeSitter,
 		"java":       EngineTreeSitter,
 		"c":          EngineTreeSitter,
-		"cpp":        EngineTreeSitter,
-		"c++":        EngineTreeSitter,
 		"scala":      EngineTreeSitter,
 		"rust":       EngineTreeSitter,
-		"ruby":       EngineTreeSitter,
 		"c#":         EngineTreeSitter,
 		"jsonnet":    EngineTreeSitter,
 		"xlsg":       EngineTreeSitter,