Auto merge of #112346 - saethlin:no-comment, r=oli-obk

Remove comments from mir-opt MIR dumps

See https://rust-lang.zulipchat.com/#narrow/stream/189540-t-compiler.2Fwg-mir-opt/topic/Line.20numbers.20in.20mir-opt.20tests/near/363849874

In rust-lang/rust#99780 there is mention that "there has been a zulip conversation about disabling line numbers with mixed opinions" which to me means that some people opposed this. I can't find the referenced conversation so... here we go.

The current situation is quite chaotic. It's not hard to find MIR diffs which contain

* Absolute line numbers
* Relative line numbers
* Substituted line numbers (LL)
For example: https://github.com/rust-lang/rust/blob/408bbd040613f6776e0a7d05d582c81f4ddc189a/tests/mir-opt/inline/inline_shims.drop.Inline.diff#L10-L17

And sometimes adding a comment at the top of a mir-opt test generates a diff in the test because a line number changed: https://github.com/rust-lang/rust/pull/98112/files#diff-b8cf4bcce95078e6a3faf075e9abf6864872fb28a64d95c04f04513b9e3bbd81

And irrelevant changes to the standard library can generate diffs in mir-opt tests: https://github.com/rust-lang/rust/pull/110694/files#diff-bf96b0e7c67b8b272814536888fd9428c314991e155beae1f0a2a67f0ac47b2c
rust-lang/rust@769886c

I think we should, specifically in mir-opt tests, completely remove the comments, or insert placeholders for all line and column numbers.

Author: bors