tidy: enable readability-redundant-string-init #25705

Remove unnecessary std::string = "" initializations. Enable readability-redundant-string-init.

See: https://releases.llvm.org/14.0.0/tools/clang/tools/extra/docs/clang-tidy/checks/readability-redundant-string-init.html

ACK 49168df073d465450b1da4a506ac7ea24fbbb87

• I agree with adding the redundant string init clang-tidy check, as this makes the code cleaner and free of redundancies.
• Verified that the clang-tidy check works perfectly, and Commit-1 covers all the instances of the check by:

1. Resetting the branch to master.
2. Cherry-picking the commit, adding the clang-tidy test.
3. Running the clang-tidy test as per instructions in https://github.com/bitcoin/bitcoin/blob/master/doc/developer-notes.md

Not sure about readability failing checks. There seems to be no risk in leaving this as the original author picked it, just like picking a variable name.

Also, given that a CI failure will not print the error easily accessible right now, I can think that readability checks may frustrate contributors.

There seems to be no risk in leaving this as the original author picked it, just like picking a variable name.

There might be no risk, but there's also no point to the code being removed. It's just verbose, and inconsistent with the rest of the codebase. I disagree that this is somehow similar to picking variable names.

Well, fine then. Though, I still think we should make the dev UX better than "lol, CI is red, go figure out how to download a 100KB text file and grep for error".

Though, I still think we should make the dev UX better than "lol, CI is red, go figure out how to download a 100KB text file and grep for error".

Started improving that in #25713.

It probably doesn't matter for this check, but we should keep it in mind with more checks being enabled regularly now.