Let enry decide the filetype unconditionally for code highlighting

[SuperAuguste]

Closes #56372

Test plan

Add tests.

[sourcegraph-bot]

Codenotify: Notifying subscribers in CODENOTIFY files for diff 82df680...e6b4430.

Notify	File(s)
@efritz	lib/codeintel/languages/BUILD.bazel lib/codeintel/languages/languages.go

[varungandhi-src]

Alternate comment suggestion: Set a soft upper limit on the time spent to determine the language, as this code path is triggered for every syntax highlighting request.

(Optional) Additionally, the number 2048 seems arbitrary; could you roughly benchmark the time spent for some large C++ files? It would be nice to know much time this takes.

[varungandhi-src]

Also, add a comment that this number shouldn't be reduced below 755 as the Apache License text has that many characters.

(Otherwise, for .h header files with Apache License headers, we may get confused between C and C++)

[SuperAuguste]

Oh I just copied this code from zoekt so I'm not sure what logic they used, but I can look into it if you like.

[varungandhi-src]

I don't think it particularly matters what exact reasoning Zoekt used; this code snippet is small enough that we can independently determine what a good limit should be.

[varungandhi-src]

This looks directionally correct, I've left some minor comments to make things more idiomatic and clearer in terms of why certain decisions were made and what some potential footguns are.

Also, you forgot to add a Test Plan in the PR description, it can be as simple as "Added new unit tests"

[SuperAuguste]

Thanks @varungandhi-src, this helps a lot! :)