Fix: avoid generating nested comments when not supported

[georgesittas]

Fixes #5132

[github-actions]

Parsing Benchmark

Benchmark	bench_parse_pr	bench_parse_main
parse_sqlglot_tpch	5.64 ms	5.58 ms: 1.01x faster
parse_sqlglot_short	349 us	347 us: 1.01x faster
parse_sqlglotrs_tpch	4.11 ms	4.05 ms: 1.01x faster
Geometric mean	(ref)	1.00x faster

Benchmark hidden because not significant (5): parse_sqlglot_long, parse_sqlglot_crazy, parse_sqlglotrs_short, parse_sqlglotrs_long, parse_sqlglotrs_crazy

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Optimization Benchmark

Benchmark	bench_optimize_pr	bench_optimize_main
optimize_tpch	740 ms	747 ms: 1.01x slower
optimize_condition_100	89.8 ms	91.0 ms: 1.01x slower
optimize_condition_1000	2.85 sec	2.89 sec: 1.01x slower
Geometric mean	(ref)	1.01x slower

Benchmark hidden because not significant (1): optimize_condition_10