Remove is_current_token_postfix

[dhruvmanila]

Summary

This PR removes the is_current_token_postifx method and instead directly calls the parse_postifx_expression. The condition was required because postfix expression parsing would reset the is_parenthesized field on the ParsedExpr. Now, we'll make that explicit.

[codspeed-hq]

CodSpeed Performance Report

Merging #10855 will degrade performances by 5.78%

_{Comparing dhruv/remove-is-current-postfix (a0dc22a) with dhruv/parser (38d649c)}

Summary

⚡ 2 improvements
❌ 1 regressions
✅ 27 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	dhruv/parser	dhruv/remove-is-current-postfix	Change
⚡	parser[large/dataset.py]	28.7 ms	26.7 ms	+7.66%
⚡	parser[pydantic/types.py]	11.8 ms	10.9 ms	+8.19%
❌	parser[unicode/pypinyin.py]	1.6 ms	1.7 ms	-5.78%

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

Formatter (stable)

✅ ecosystem check detected no format changes.

Formatter (preview)

✅ ecosystem check detected no format changes.