Show errors for attempted fixes only when passed --verbose (#15237)

The default logging level for diagnostics includes logs written using
the `log` crate with level `error`, `warn`, and `info`. An unsuccessful
fix attached to a diagnostic via `try_set_fix` or `try_set_optional_fix`
was logged at level `error`. Note that the user would see these messages
even without passing `--fix`, and possibly also on lines with `noqa`
comments.

This PR changes the logging level here to a `debug`. We also found
ad-hoc instances of error logging in the implementations of several
rules, and have replaced those with either a `debug` or call to
`try_set{_optional}_fix`.

Closes #15229

crates/ruff_diagnostics/src/diagnostic.rs

@@ -1,5 +1,5 @@
 use anyhow::Result;
-use log::error;
+use log::debug;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
@@ -56,7 +56,7 @@ impl Diagnostic {
     pub fn try_set_fix(&mut self, func: impl FnOnce() -> Result<Fix>) {
         match func() {
             Ok(fix) => self.fix = Some(fix),
-            Err(err) => error!("Failed to create fix for {}: {}", self.kind.name, err),
+            Err(err) => debug!("Failed to create fix for {}: {}", self.kind.name, err),
         }
     }
 
@@ -67,7 +67,7 @@ impl Diagnostic {
         match func() {
             Ok(None) => {}
             Ok(Some(fix)) => self.fix = Some(fix),
-            Err(err) => error!("Failed to create fix for {}: {}", self.kind.name, err),
+            Err(err) => debug!("Failed to create fix for {}: {}", self.kind.name, err),
         }
     }