[clang-tools-extra] [clang-tidy] Don't print `Enabled checks:` by default (PR #185229)

[Baranov Victor via cfe-commits]

vbvictor wrote:

> If anything it could print the list once at the very beginning of the CI run, but not for each .cpp file.

As [nicovank](https://github.com/nicovank) mentioned it's only printed once per whole run (in the beginning)

> I agree tools should typically not be so verbose by default. The only time one needs to see it is when setting up/troubleshooting CI, but not the many more times that CI runs.

Historically clang-tidy is verbose by default and can be quiet with `-quiet` flag. The same pattern is implemented in `run-clang-tidy` with `-quiet` flag that suppresses "list-checks" output.
So when CI is set up, one can use `-quiet` flag to suppress undesired output.
I can see a solution when we make `run-clang-tidy` (and clang-tidy) quiet by default and add `-verbose` flag instead, but will be a breaking change. I don't think we should bring breaking changes unless strong consensus is reached.

I'm against simply removing diagnostics with no way of enabling them.

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> "not human readable at all" means that it became barely usable in case of 500+ lines of checks listed each time. It became a huge block of text which is hard to scroll.
How often do we need to look into this Enabled checks: block?

We want to look at it when something went wrong in CI. For locar runs, doesn't `-quiet` solve your problem?

https://github.com/llvm/llvm-project/pull/185229