Preserve parentheses around left side of binary expression

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## Summary

This PR fixes an issue where the binary expression formatting removed parentheses around the left hand side of an expression.

<!-- What's the purpose of the change? What does it do, and why? -->

## Test Plan

I added a new regression test and re-ran the ecosystem check. It brings down the `check-formatter-stability` output from a 3.4MB file down to 900KB. 

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crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/binary.py

@@ -205,3 +205,9 @@ if (
 # Unstable formatting in https://github.com/realtyem/synapse-unraid/blob/unraid_develop/synapse/handlers/presence.py
 for user_id in set(target_user_ids) - {u.user_id for u in updates}:
     updates.append(UserPresenceState.default(user_id))
+
+# Keeps parenthesized left hand sides
+(
+    log(self.price / self.strike)
+    + (self.risk_free - self.div_cont + 0.5 * (self.sigma**2)) * self.exp_time
+) / self.sigmaT